https://orcid.org/0000-0001-9189-6495
Abstract
Post-coronovirus disease (COVID) symptoms can persist several months after severe acute respiratory syndrome coronavirus 2 infection. Little is known, however, about the prevalence of post-COVID condition following infections from Omicron variants and how this varies according to vaccination status. This study evaluates the prevalence of symptoms and functional impairment 12 weeks after an infection by Omicron variants (BA.1 and BA.2) compared with negative controls tested during the same period.
Outpatient individuals who tested positive or negative for COVID-19 infection between December 2021 and February 2022 at the Geneva University Hospitals were followed 12 weeks after their test date.
Overall, 11.7% of Omicron cases had symptoms 12 weeks after the infection compared with 10.4% of individuals who tested negative during the same period (P < .001), and symptoms were much less common in vaccinated versus nonvaccinated individuals with Omicron infection (9.7% vs 18.1%; P < .001). There were no significant differences in functional impairment at 12 weeks between Omicron cases and negative controls, even after adjusting for multiple potential confounders.
The differential prevalence of post-COVID symptoms and functional impairment attributed to Omicron BA.1 and BA.2 infection is low when compared with negative controls. Vaccination is associated with lower prevalence of post-COVID symptoms.
Post-coronovirus disease (COVID) condition or post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can persist several months after SARS-CoV-2 infection [1, 2]. The prevalence of post-COVID conditions has been estimated at almost 30% after an infection [3, 4] and is seen in outpatient [3] and inpatient [5] settings. This, in turn, is associated with functional impairment and worsening quality of life [1, 6], and potentially leads to a substantial economic impact on a societal level [7]. A recent report estimated that 16 million working-age Americans could have post-COVID today, and 2–4 million are out of work due to post-COVID, with an estimated annual cost of $170 billion per year attributed to lost wages [7].
This has led scientists to explore the underlying pathophysiology and to try to understand the mechanisms leading to this high prevalence of post-COVID symptoms [8–10], with very few answers to date. In general, patients who experience post-COVID condition [2] describe fatigue as the most prevalent and persistent symptom [1], as well as neurocognitive symptoms associated with long-term functional impairment, increased utilization of healthcare resources, and an overall worsening state of health and quality of life [6, 11].
To date, the estimates of the prevalence of post-COVID symptoms and functional impairment are mostly based on early variants of SARS-CoV-2 [1, 4, 5], and estimates after Omicron infection are not yet established. A recent report [12] showed a prevalence of post-COVID symptoms in 4.5% of Omicron cases compared with 10.8% of Delta cases, 4 weeks after the infection [12]. Results in this study were limited by the self-reported nature of the infection as well as the short duration of follow-up. The consensus and generally agreed-upon definition of post-COVID condition established by the World Health Organization describes symptoms that persist at least 12 weeks after the infection after excluding other causes [2]. While in clinical practice it is important to detect cases as early as possible, more research is needed to define the prevalence of persistent symptoms 12 weeks after Omicron infection. A recent communication [13] suggested that, out of 428 individuals hospitalized for coronavirus disease 2019 (COVID-19; Omicron variants), 76% had persistent symptoms 4–12 weeks after their infection. It is important to note that post-COVID condition differs between inpatient and outpatient settings [14], and extrapolation to the overall prevalence of post-COVID condition in this context is difficult, with the majority of infections occurring in outpatient settings after Omicron infection. The prevalence of post-COVID condition after Omicron infection has thus not yet been established.
This study evaluates the prevalence of symptoms and functional impairment 12 weeks after an infection by Omicron variants (BA.1 and BA.2), accounting for vaccination, compared with individuals who tested negative during the same period.
METHODS
Geneva, Switzerland, is a state (canton) of approximately 500 000 residents, with 40% of the population composed of foreigners from different nationalities. Approximately 73% of foreigners are European, 9.1% from Africa, 9% from the Americas, and 8.5% from Asia. All individuals have universal healthcare access and coverage. The Geneva University Hospitals (1920 beds) is the only public university hospital and the largest healthcare facility in the canton. The CoviCare program [1, 3] is a longitudinal study of individuals tested for SARS-CoV-2 (nasal swab reverse transcriptase–polymerase chain reaction [RT-PCR]) at the Geneva University Hospitals outpatient testing center. Individuals benefit from regular follow-ups every 3 to 6 months to evaluate the prevalence of post-COVID condition and the evolution of symptoms.
In this study, individuals tested between 17 December 2021 and 13 February 2022 were contacted 3 months after their test date. All individuals gave consent, and the study was approved by the Cantonal Research Ethics Commission of Geneva, Switzerland (protocol number 2021-00389). Only individuals with a laboratory-confirmed test date were included in this study. Individuals having had a prior infection (documented or self-reported), those who reported an infection between their test date and follow-up, and those with incomplete data were excluded.
Follow-up was conducted via an online questionnaire using REDCap, and the follow-up instrument included questions about baseline characteristics, symptoms at time of testing, general health and comorbidities, symptoms at the time of follow-up, functional capacity, and quality of life. Only symptoms with a new onset after the test date were taken into consideration. Age categories were defined as “below 40,” “40–59 years,” and “60 years and above” on the basis of previous studies suggesting that middle age may be a predictor of persistent symptoms [15]. The Chalder Fatigue Scale [16] and the Eastern Cooperative Oncology Group performance scale [17] were used to evaluate fatigue when present; the modified Medical Research Council scale was used to evaluate dyspnea [18]. Sleeping disorders were assessed using the Insomnia Severity Index [19], and psychiatric conditions assessed using the Hospital Anxiety and Depression Scale [20]. All symptoms were also assessed using a Likert scale with self-reported options of “mild,” “moderate,” or “severe” for intensity at time of follow-up. A Likert scale was also used to assess symptom frequency in the 2 weeks preceding the follow-up, with self-reported options of “never,” “rarely,” “often,” or “always.” The Sheehan Disability Scale [21] was used to assess functional capacity in the professional, social, and family domains using a 10-point visual scale with 0 indicating no impairment at all, 1–3 indicating mild impairment, 4–6 indicating moderate impairment, 7–9 indicating marked impairment, and 10 indicating extreme impairment. Days lost and days with reduced productivity due to functional impairment [21] in the week preceding the survey were also assessed. Self-rated health was assessed using the first question of the 12-item Short Form (SF-12) questionnaire [22] consisting of a Likert scale of excellent, very good, good, fair, and poor; answers were later categorized into 2 categories: 0 (poor to fair) and 1 (good to excellent). The complete survey instrument is available in Supplementary Table 1.
Data were collected using REDCap version 11.0.3 and analyzed using the statistical software Stata, version 16.0 (StataCorp). Descriptive analyses included percentages with comparisons using chi-square tests and Student's t test. A P value of less than .05 was considered significant. Estimates of the prevalence of symptoms and functional impairment using a linear regression adjusted for age, sex, vaccination status, monoclonal antibody treatment during the acute phase, time from infection, and the following pre-existing comorbidities: obesity or overweight, hypertension, diabetes, respiratory disease, cardiovascular disease, headache disorders, cognitive disorders, sleep disorders, depression, anxiety, hypothyroidism, rheumatologic disease, anemia, chronic pain or fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome. Logistic regression models were used to evaluate associations between Omicron infection (BA.1 and BA.2) with functional impairment compared with negative controls. Only individuals reporting new symptom onset at testing were included in the regression analysis. The outcome of functional impairment was defined as having mild, moderate, or severe functional impairment using the Sheehan Disability Scale [21] at the time of follow-up. Adjusted odds ratios (aORs) were adjusted for time from infection, age, sex, vaccination status, monoclonal antibody treatment during the acute phase, and the following pre-existing comorbidities: obesity or overweight, hypertension, diabetes, respiratory disease, cardiovascular disease, headache disorders, cognitive disorders, sleep disorders, depression, anxiety, hypothyroidism, rheumatologic disease, anemia, chronic pain or fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome.
Considering there was potential overlap between Delta and Omicron variants between 17 December 2021 and 16 January 2022, a subgroup analysis was conducted including only samples with confirmatory sequencing during that time period (10% of overall samples). The sequencing for the “S drop out” by an additional RT-PCR (TaqPath; ThermoFisher) was indicative of the Omicron BA.1 variant. Additional whole-genome sequencing using an amplicon-based sequencing approach allowed for definitive confirmation. Considering there was a prevalence of more than 98% Omicron BA.1 and BA.2 infections between 17 January and 13 February 2022, all individuals tested during that time period were included independently of confirmatory sequencing [23].
An additional subgroup analysis evaluated the prevalence of symptoms in vaccinated and nonvaccinated individuals, based on studies showing the potential role of vaccination in the acute and postacute phases of SARS-CoV-2 infection [24, 25].
RESULTS
Study Participants
Overall, 3507 individuals participated in this follow-up out of 11 305 invited to participate (response rate: 31.0%). Of participants, 597 had incomplete answers and were excluded from this study. Of participants who completed the follow-up (n = 2910), 1021 tested negative and 1889 tested positive. Additionally, 139 of those who tested negative at the Geneva University Hospitals during that time period reported having had a more recent positive test outside of the Geneva University Hospitals and were excluded; 82 of those who tested positive at the Geneva University Hospitals reported having had a second more recent positive test and were also excluded. After excluding those with positive test results outside of the Geneva University Hospitals, 1807 individuals who tested positive and 882 individuals who tested negative were included (Figure 1). The mean follow-up time was 83 (standard deviation [SD]: 12.3) days after the test result for those who tested positive and 84 (SD: 12.4) days for those who tested negative. Characteristics of SARS-CoV-2 Omicron-positive individuals and individuals who tested negative are presented in Table 1. In the 2 groups, the mean (SD) age was 41.6 (13.5) years versus 43.7 (14.9) years, 62.3% versus 63.9% were women, 74.0% versus 78.6% were vaccinated with at least 2 doses (61.2% Moderna COVID-19 vaccine [mRNA-1273]; 36.1% Pfizer-Biontech Comirnaty BNT162b2), and 44.0% versus 48.9% had no pre-existing comorbidities. Additionally, 12.8% of Omicron cases had recourse to treatment after the infection (anti-inflammatory drugs, paracetamol in general) compared to 10.5% of SARS-CoV-2–negative individuals (P = .116).
Study flowchart. Only individuals with a laboratory-confirmed test date were included in this study. Individuals who had a prior infection (documented or self-reported) were excluded. Overall, 3507 individuals participated in this follow-up out of 11 305 invited to participate (response rate: 31.0%). Of participants, 597 had incomplete answers and were excluded from this study. Additionally, 139 of those who tested negative at the Geneva University Hospitals during that time period reported having had a positive test outside of the Geneva University Hospitals and were excluded; 82 of those who tested positive at the Geneva University Hospitals reported having had a second, more recent positive test and were also excluded. Abbreviation: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Baseline Characteristics in Individuals Who Tested Positive and Negative for SARS-CoV-2 During the Omicron BA.1 and BA.2 Pandemic Wave (N = 2689)
| Total (N = 2689) | SARS-CoV-2 Omicron (BA.1/BA.2) Positive (n = 1807) | SARS-CoV-2 Negative (n = 882) | P | |
|---|---|---|---|---|
| Age categories | .001 | |||
| ȃ<40 years | 1263 (47.0) | 877 (48.6) | 386 (43.8) | |
| ȃ40–59 years | 1122 (41.7) | 752 (41.6) | 370 (41.9) | |
| ȃ≥60 years | 304 (11.3) | 178 (9.9) | 126 (14.3) | |
| Sex | .426 | |||
| ȃMale | 1000 (37.2) | 681 (37.7) | 319 (36.1) | |
| ȃFemale | 1689 (62.8) | 1126 (62.3) | 564 (63.9) | |
| Education | .106 | |||
| ȃPrimary | 161 (6) | 113 (6.3) | 48 (5.4) | |
| ȃApprenticeship | 318 (11.8) | 234 (12.9) | 84 (9.5) | |
| ȃSecondary | 415 (15.4) | 283 (15.7) | 132 (15) | |
| ȃTertiary | 1634 (60.8) | 1069 (59.2) | 565 (64.1) | |
| ȃOther | 98 (3.6) | 66 (3.7) | 32 (3.6) | |
| ȃPrefer not to answer | 63 (2.3) | 42 (2.3) | 21 (2.4) | |
| Civil status | .040 | |||
| ȃSingle | 588 (21.9) | 378 (20.9) | 210 (23.8) | |
| ȃLiving with a partner or other people, not married | 715(26.6) | 505 (27.9) | 210 (23.8) | |
| ȃMarried or registered partnership | 1104 (41.1) | 750 (41.5) | 354 (40.1) | |
| ȃDivorced or separated | 238 (8.9) | 149 (8.2) | 89 (10.1) | |
| ȃWidowed | 33 (1.2) | 20 (1.1) | 13 (1.5) | |
| ȃOther | 11 (0.4) | 5 (0.3) | 6 (0.7) | |
| Has kids | 1598 (59.4) | 1093 (60.5) | 505 (57.3) | .109 |
| Current pregnancy | 36 (1.3) | 28 (1.5) | 8 (0.9) | .123 |
| Living situation | <.001 | |||
| ȃAlone | 441 (16.4) | 277 (15.3) | 164 (18.6) | |
| ȃSingle parent with children | 224 (8.3) | 141 (7.8) | 83 (9.4) | |
| ȃLiving with a partner, without children | 559 (20.8) | 352 (19.5) | 207 (23.5) | |
| ȃLiving with a partner, with children | 1057 (39.3) | 760 (42.1) | 297 (33.7) | |
| ȃCohabitation | 408 (15.2) | 277 (15.3) | 131 (14.9) | |
| Work status | <.001 | |||
| ȃSalaried | 1801 (67) | 1236 (68.4) | 565 (64.1) | |
| ȃRetired | 161 (6) | 81 (4.5) | 80 (9.1) | |
| ȃStudent or in training | 298 (11.1) | 201 (11.1) | 97 (11) | |
| ȃIndependent worker | 163 (6.1) | 106 (5.9) | 57 (6.5) | |
| ȃHomemaker | 81 (3) | 59 (3.3) | 22 (2.5) | |
| ȃUnemployed | 101 (3.8) | 68 (3.8) | 33 (3.7) | |
| ȃDisability | 35 (1.3) | 19 (1.1) | 16 (1.8) | |
| ȃOther | 49 (1.8) | 37 (2) | 12 (1.4) | |
| Smoking status | .061 | |||
| ȃNever smoked | 1390 (51.7) | 946 (52.4) | 444 (50.3) | |
| ȃCurrent smoker | 532 (19.8) | 338 (18.7) | 194 (22) | |
| ȃEx-smoker | 689 (25.6) | 469 (25.9) | 220 (24.9) | |
| ȃPrefer not to answer | 78 (2.9) | 54 (3) | 24 (2.7) | |
| Physical activity | .896 | |||
| ȃNo physical activity | 410 (15.2) | 278 (15.4) | 132 (15) | |
| ȃPartial physical activity | 1408 (52.4) | 939 (52) | 469 (53.2) | |
| ȃComplete physical activity | 849 (31.6) | 574 (31.8) | 275 (31.2) | |
| ȃPrefer not to answer | 22 (0.8) | 16 (0.9) | 6 (0.7) | |
| Vaccination | <.001 | |||
| ȃNo vaccination | 397 (14.8) | 287 (15.9) | 110 (12.5) | |
| ȃ1 dose | 151 (5.6) | 107 (5.9) | 44 (5.0) | |
| ȃFully vaccinated (2–3 doses) | 2031 (75.5) | 1338 (74.0) | 693 (78.6) | |
| ȃPrefer not to answer | 21 (0.8) | 15 (0.8) | 6 (0.7) | |
| ȃNo information | 89 (3.3) | 60 (3.3) | 29 (3.3) | |
| Self-rated health at time of testing | .012 | |||
| ȃPoor | 237 (8.8) | 142 (7.9) | 95 (10.8) | |
| ȃGood | 2452 (91.2) | 1665 (92.1) | 787 (89.2) | |
| Comorbidities | ||||
| ȃObesity or overweight | 338 (12.6) | 231 (12.8) | 107 (12.1) | .621 |
| ȃHypertension | 159 (5.9) | 99 (5.5) | 60 (6.8) | .175 |
| ȃDiabetes | 44 (1.6) | 29 (1.6) | 15 (1.7) | .858 |
| ȃRespiratory disease | 114 (4.2) | 74 (4.1) | 40 (4.5) | .601 |
| ȃCardiovascular disease | 43 (1.6) | 23 (1.3) | 20 (2.3) | .054 |
| ȃHeadache disorders | 288 (10.7) | 177 (9.8) | 111 (12.6) | .029 |
| ȃSleep disorders | 250 (9.3) | 167 (9.2) | 83 (9.4) | .898 |
| ȃCognitive disorders | 155 (5.8) | 104 (5.8) | 51 (5.8) | .986 |
| ȃHyperthyroidism | 13 (0.5) | 5 (0.3) | 8 (0.9) | .027 |
| ȃHypothyroidism | 56 (2.1) | 36 (2) | 20 (2.3) | .643 |
| ȃDepression | 126 (4.7) | 76 (4.2) | 50 (5.7) | .094 |
| ȃAnxiety | 186 (6.9) | 127 (7) | 59 (6.7) | .737 |
| ȃRheumatological disorders | 168 (6.2) | 110 (6.1) | 58 (6.6) | .631 |
| ȃAnemia | 79 (2.9) | 50 (2.8) | 29 (3.3) | .457 |
| ȃChronic pain or fibromyalgia | 32 (1.2) | 20 (1.1) | 12 (1.4) | .572 |
| ȃIrritable bowel syndrome | 107 (4) | 63 (3.5) | 44 (5) | .063 |
| Total (N = 2689) | SARS-CoV-2 Omicron (BA.1/BA.2) Positive (n = 1807) | SARS-CoV-2 Negative (n = 882) | P | |
|---|---|---|---|---|
| Age categories | .001 | |||
| ȃ<40 years | 1263 (47.0) | 877 (48.6) | 386 (43.8) | |
| ȃ40–59 years | 1122 (41.7) | 752 (41.6) | 370 (41.9) | |
| ȃ≥60 years | 304 (11.3) | 178 (9.9) | 126 (14.3) | |
| Sex | .426 | |||
| ȃMale | 1000 (37.2) | 681 (37.7) | 319 (36.1) | |
| ȃFemale | 1689 (62.8) | 1126 (62.3) | 564 (63.9) | |
| Education | .106 | |||
| ȃPrimary | 161 (6) | 113 (6.3) | 48 (5.4) | |
| ȃApprenticeship | 318 (11.8) | 234 (12.9) | 84 (9.5) | |
| ȃSecondary | 415 (15.4) | 283 (15.7) | 132 (15) | |
| ȃTertiary | 1634 (60.8) | 1069 (59.2) | 565 (64.1) | |
| ȃOther | 98 (3.6) | 66 (3.7) | 32 (3.6) | |
| ȃPrefer not to answer | 63 (2.3) | 42 (2.3) | 21 (2.4) | |
| Civil status | .040 | |||
| ȃSingle | 588 (21.9) | 378 (20.9) | 210 (23.8) | |
| ȃLiving with a partner or other people, not married | 715(26.6) | 505 (27.9) | 210 (23.8) | |
| ȃMarried or registered partnership | 1104 (41.1) | 750 (41.5) | 354 (40.1) | |
| ȃDivorced or separated | 238 (8.9) | 149 (8.2) | 89 (10.1) | |
| ȃWidowed | 33 (1.2) | 20 (1.1) | 13 (1.5) | |
| ȃOther | 11 (0.4) | 5 (0.3) | 6 (0.7) | |
| Has kids | 1598 (59.4) | 1093 (60.5) | 505 (57.3) | .109 |
| Current pregnancy | 36 (1.3) | 28 (1.5) | 8 (0.9) | .123 |
| Living situation | <.001 | |||
| ȃAlone | 441 (16.4) | 277 (15.3) | 164 (18.6) | |
| ȃSingle parent with children | 224 (8.3) | 141 (7.8) | 83 (9.4) | |
| ȃLiving with a partner, without children | 559 (20.8) | 352 (19.5) | 207 (23.5) | |
| ȃLiving with a partner, with children | 1057 (39.3) | 760 (42.1) | 297 (33.7) | |
| ȃCohabitation | 408 (15.2) | 277 (15.3) | 131 (14.9) | |
| Work status | <.001 | |||
| ȃSalaried | 1801 (67) | 1236 (68.4) | 565 (64.1) | |
| ȃRetired | 161 (6) | 81 (4.5) | 80 (9.1) | |
| ȃStudent or in training | 298 (11.1) | 201 (11.1) | 97 (11) | |
| ȃIndependent worker | 163 (6.1) | 106 (5.9) | 57 (6.5) | |
| ȃHomemaker | 81 (3) | 59 (3.3) | 22 (2.5) | |
| ȃUnemployed | 101 (3.8) | 68 (3.8) | 33 (3.7) | |
| ȃDisability | 35 (1.3) | 19 (1.1) | 16 (1.8) | |
| ȃOther | 49 (1.8) | 37 (2) | 12 (1.4) | |
| Smoking status | .061 | |||
| ȃNever smoked | 1390 (51.7) | 946 (52.4) | 444 (50.3) | |
| ȃCurrent smoker | 532 (19.8) | 338 (18.7) | 194 (22) | |
| ȃEx-smoker | 689 (25.6) | 469 (25.9) | 220 (24.9) | |
| ȃPrefer not to answer | 78 (2.9) | 54 (3) | 24 (2.7) | |
| Physical activity | .896 | |||
| ȃNo physical activity | 410 (15.2) | 278 (15.4) | 132 (15) | |
| ȃPartial physical activity | 1408 (52.4) | 939 (52) | 469 (53.2) | |
| ȃComplete physical activity | 849 (31.6) | 574 (31.8) | 275 (31.2) | |
| ȃPrefer not to answer | 22 (0.8) | 16 (0.9) | 6 (0.7) | |
| Vaccination | <.001 | |||
| ȃNo vaccination | 397 (14.8) | 287 (15.9) | 110 (12.5) | |
| ȃ1 dose | 151 (5.6) | 107 (5.9) | 44 (5.0) | |
| ȃFully vaccinated (2–3 doses) | 2031 (75.5) | 1338 (74.0) | 693 (78.6) | |
| ȃPrefer not to answer | 21 (0.8) | 15 (0.8) | 6 (0.7) | |
| ȃNo information | 89 (3.3) | 60 (3.3) | 29 (3.3) | |
| Self-rated health at time of testing | .012 | |||
| ȃPoor | 237 (8.8) | 142 (7.9) | 95 (10.8) | |
| ȃGood | 2452 (91.2) | 1665 (92.1) | 787 (89.2) | |
| Comorbidities | ||||
| ȃObesity or overweight | 338 (12.6) | 231 (12.8) | 107 (12.1) | .621 |
| ȃHypertension | 159 (5.9) | 99 (5.5) | 60 (6.8) | .175 |
| ȃDiabetes | 44 (1.6) | 29 (1.6) | 15 (1.7) | .858 |
| ȃRespiratory disease | 114 (4.2) | 74 (4.1) | 40 (4.5) | .601 |
| ȃCardiovascular disease | 43 (1.6) | 23 (1.3) | 20 (2.3) | .054 |
| ȃHeadache disorders | 288 (10.7) | 177 (9.8) | 111 (12.6) | .029 |
| ȃSleep disorders | 250 (9.3) | 167 (9.2) | 83 (9.4) | .898 |
| ȃCognitive disorders | 155 (5.8) | 104 (5.8) | 51 (5.8) | .986 |
| ȃHyperthyroidism | 13 (0.5) | 5 (0.3) | 8 (0.9) | .027 |
| ȃHypothyroidism | 56 (2.1) | 36 (2) | 20 (2.3) | .643 |
| ȃDepression | 126 (4.7) | 76 (4.2) | 50 (5.7) | .094 |
| ȃAnxiety | 186 (6.9) | 127 (7) | 59 (6.7) | .737 |
| ȃRheumatological disorders | 168 (6.2) | 110 (6.1) | 58 (6.6) | .631 |
| ȃAnemia | 79 (2.9) | 50 (2.8) | 29 (3.3) | .457 |
| ȃChronic pain or fibromyalgia | 32 (1.2) | 20 (1.1) | 12 (1.4) | .572 |
| ȃIrritable bowel syndrome | 107 (4) | 63 (3.5) | 44 (5) | .063 |
Data are presented as no. (%). Abbreviation: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Baseline Characteristics in Individuals Who Tested Positive and Negative for SARS-CoV-2 During the Omicron BA.1 and BA.2 Pandemic Wave (N = 2689)
| Total (N = 2689) | SARS-CoV-2 Omicron (BA.1/BA.2) Positive (n = 1807) | SARS-CoV-2 Negative (n = 882) | P | |
|---|---|---|---|---|
| Age categories | .001 | |||
| ȃ<40 years | 1263 (47.0) | 877 (48.6) | 386 (43.8) | |
| ȃ40–59 years | 1122 (41.7) | 752 (41.6) | 370 (41.9) | |
| ȃ≥60 years | 304 (11.3) | 178 (9.9) | 126 (14.3) | |
| Sex | .426 | |||
| ȃMale | 1000 (37.2) | 681 (37.7) | 319 (36.1) | |
| ȃFemale | 1689 (62.8) | 1126 (62.3) | 564 (63.9) | |
| Education | .106 | |||
| ȃPrimary | 161 (6) | 113 (6.3) | 48 (5.4) | |
| ȃApprenticeship | 318 (11.8) | 234 (12.9) | 84 (9.5) | |
| ȃSecondary | 415 (15.4) | 283 (15.7) | 132 (15) | |
| ȃTertiary | 1634 (60.8) | 1069 (59.2) | 565 (64.1) | |
| ȃOther | 98 (3.6) | 66 (3.7) | 32 (3.6) | |
| ȃPrefer not to answer | 63 (2.3) | 42 (2.3) | 21 (2.4) | |
| Civil status | .040 | |||
| ȃSingle | 588 (21.9) | 378 (20.9) | 210 (23.8) | |
| ȃLiving with a partner or other people, not married | 715(26.6) | 505 (27.9) | 210 (23.8) | |
| ȃMarried or registered partnership | 1104 (41.1) | 750 (41.5) | 354 (40.1) | |
| ȃDivorced or separated | 238 (8.9) | 149 (8.2) | 89 (10.1) | |
| ȃWidowed | 33 (1.2) | 20 (1.1) | 13 (1.5) | |
| ȃOther | 11 (0.4) | 5 (0.3) | 6 (0.7) | |
| Has kids | 1598 (59.4) | 1093 (60.5) | 505 (57.3) | .109 |
| Current pregnancy | 36 (1.3) | 28 (1.5) | 8 (0.9) | .123 |
| Living situation | <.001 | |||
| ȃAlone | 441 (16.4) | 277 (15.3) | 164 (18.6) | |
| ȃSingle parent with children | 224 (8.3) | 141 (7.8) | 83 (9.4) | |
| ȃLiving with a partner, without children | 559 (20.8) | 352 (19.5) | 207 (23.5) | |
| ȃLiving with a partner, with children | 1057 (39.3) | 760 (42.1) | 297 (33.7) | |
| ȃCohabitation | 408 (15.2) | 277 (15.3) | 131 (14.9) | |
| Work status | <.001 | |||
| ȃSalaried | 1801 (67) | 1236 (68.4) | 565 (64.1) | |
| ȃRetired | 161 (6) | 81 (4.5) | 80 (9.1) | |
| ȃStudent or in training | 298 (11.1) | 201 (11.1) | 97 (11) | |
| ȃIndependent worker | 163 (6.1) | 106 (5.9) | 57 (6.5) | |
| ȃHomemaker | 81 (3) | 59 (3.3) | 22 (2.5) | |
| ȃUnemployed | 101 (3.8) | 68 (3.8) | 33 (3.7) | |
| ȃDisability | 35 (1.3) | 19 (1.1) | 16 (1.8) | |
| ȃOther | 49 (1.8) | 37 (2) | 12 (1.4) | |
| Smoking status | .061 | |||
| ȃNever smoked | 1390 (51.7) | 946 (52.4) | 444 (50.3) | |
| ȃCurrent smoker | 532 (19.8) | 338 (18.7) | 194 (22) | |
| ȃEx-smoker | 689 (25.6) | 469 (25.9) | 220 (24.9) | |
| ȃPrefer not to answer | 78 (2.9) | 54 (3) | 24 (2.7) | |
| Physical activity | .896 | |||
| ȃNo physical activity | 410 (15.2) | 278 (15.4) | 132 (15) | |
| ȃPartial physical activity | 1408 (52.4) | 939 (52) | 469 (53.2) | |
| ȃComplete physical activity | 849 (31.6) | 574 (31.8) | 275 (31.2) | |
| ȃPrefer not to answer | 22 (0.8) | 16 (0.9) | 6 (0.7) | |
| Vaccination | <.001 | |||
| ȃNo vaccination | 397 (14.8) | 287 (15.9) | 110 (12.5) | |
| ȃ1 dose | 151 (5.6) | 107 (5.9) | 44 (5.0) | |
| ȃFully vaccinated (2–3 doses) | 2031 (75.5) | 1338 (74.0) | 693 (78.6) | |
| ȃPrefer not to answer | 21 (0.8) | 15 (0.8) | 6 (0.7) | |
| ȃNo information | 89 (3.3) | 60 (3.3) | 29 (3.3) | |
| Self-rated health at time of testing | .012 | |||
| ȃPoor | 237 (8.8) | 142 (7.9) | 95 (10.8) | |
| ȃGood | 2452 (91.2) | 1665 (92.1) | 787 (89.2) | |
| Comorbidities | ||||
| ȃObesity or overweight | 338 (12.6) | 231 (12.8) | 107 (12.1) | .621 |
| ȃHypertension | 159 (5.9) | 99 (5.5) | 60 (6.8) | .175 |
| ȃDiabetes | 44 (1.6) | 29 (1.6) | 15 (1.7) | .858 |
| ȃRespiratory disease | 114 (4.2) | 74 (4.1) | 40 (4.5) | .601 |
| ȃCardiovascular disease | 43 (1.6) | 23 (1.3) | 20 (2.3) | .054 |
| ȃHeadache disorders | 288 (10.7) | 177 (9.8) | 111 (12.6) | .029 |
| ȃSleep disorders | 250 (9.3) | 167 (9.2) | 83 (9.4) | .898 |
| ȃCognitive disorders | 155 (5.8) | 104 (5.8) | 51 (5.8) | .986 |
| ȃHyperthyroidism | 13 (0.5) | 5 (0.3) | 8 (0.9) | .027 |
| ȃHypothyroidism | 56 (2.1) | 36 (2) | 20 (2.3) | .643 |
| ȃDepression | 126 (4.7) | 76 (4.2) | 50 (5.7) | .094 |
| ȃAnxiety | 186 (6.9) | 127 (7) | 59 (6.7) | .737 |
| ȃRheumatological disorders | 168 (6.2) | 110 (6.1) | 58 (6.6) | .631 |
| ȃAnemia | 79 (2.9) | 50 (2.8) | 29 (3.3) | .457 |
| ȃChronic pain or fibromyalgia | 32 (1.2) | 20 (1.1) | 12 (1.4) | .572 |
| ȃIrritable bowel syndrome | 107 (4) | 63 (3.5) | 44 (5) | .063 |
| Total (N = 2689) | SARS-CoV-2 Omicron (BA.1/BA.2) Positive (n = 1807) | SARS-CoV-2 Negative (n = 882) | P | |
|---|---|---|---|---|
| Age categories | .001 | |||
| ȃ<40 years | 1263 (47.0) | 877 (48.6) | 386 (43.8) | |
| ȃ40–59 years | 1122 (41.7) | 752 (41.6) | 370 (41.9) | |
| ȃ≥60 years | 304 (11.3) | 178 (9.9) | 126 (14.3) | |
| Sex | .426 | |||
| ȃMale | 1000 (37.2) | 681 (37.7) | 319 (36.1) | |
| ȃFemale | 1689 (62.8) | 1126 (62.3) | 564 (63.9) | |
| Education | .106 | |||
| ȃPrimary | 161 (6) | 113 (6.3) | 48 (5.4) | |
| ȃApprenticeship | 318 (11.8) | 234 (12.9) | 84 (9.5) | |
| ȃSecondary | 415 (15.4) | 283 (15.7) | 132 (15) | |
| ȃTertiary | 1634 (60.8) | 1069 (59.2) | 565 (64.1) | |
| ȃOther | 98 (3.6) | 66 (3.7) | 32 (3.6) | |
| ȃPrefer not to answer | 63 (2.3) | 42 (2.3) | 21 (2.4) | |
| Civil status | .040 | |||
| ȃSingle | 588 (21.9) | 378 (20.9) | 210 (23.8) | |
| ȃLiving with a partner or other people, not married | 715(26.6) | 505 (27.9) | 210 (23.8) | |
| ȃMarried or registered partnership | 1104 (41.1) | 750 (41.5) | 354 (40.1) | |
| ȃDivorced or separated | 238 (8.9) | 149 (8.2) | 89 (10.1) | |
| ȃWidowed | 33 (1.2) | 20 (1.1) | 13 (1.5) | |
| ȃOther | 11 (0.4) | 5 (0.3) | 6 (0.7) | |
| Has kids | 1598 (59.4) | 1093 (60.5) | 505 (57.3) | .109 |
| Current pregnancy | 36 (1.3) | 28 (1.5) | 8 (0.9) | .123 |
| Living situation | <.001 | |||
| ȃAlone | 441 (16.4) | 277 (15.3) | 164 (18.6) | |
| ȃSingle parent with children | 224 (8.3) | 141 (7.8) | 83 (9.4) | |
| ȃLiving with a partner, without children | 559 (20.8) | 352 (19.5) | 207 (23.5) | |
| ȃLiving with a partner, with children | 1057 (39.3) | 760 (42.1) | 297 (33.7) | |
| ȃCohabitation | 408 (15.2) | 277 (15.3) | 131 (14.9) | |
| Work status | <.001 | |||
| ȃSalaried | 1801 (67) | 1236 (68.4) | 565 (64.1) | |
| ȃRetired | 161 (6) | 81 (4.5) | 80 (9.1) | |
| ȃStudent or in training | 298 (11.1) | 201 (11.1) | 97 (11) | |
| ȃIndependent worker | 163 (6.1) | 106 (5.9) | 57 (6.5) | |
| ȃHomemaker | 81 (3) | 59 (3.3) | 22 (2.5) | |
| ȃUnemployed | 101 (3.8) | 68 (3.8) | 33 (3.7) | |
| ȃDisability | 35 (1.3) | 19 (1.1) | 16 (1.8) | |
| ȃOther | 49 (1.8) | 37 (2) | 12 (1.4) | |
| Smoking status | .061 | |||
| ȃNever smoked | 1390 (51.7) | 946 (52.4) | 444 (50.3) | |
| ȃCurrent smoker | 532 (19.8) | 338 (18.7) | 194 (22) | |
| ȃEx-smoker | 689 (25.6) | 469 (25.9) | 220 (24.9) | |
| ȃPrefer not to answer | 78 (2.9) | 54 (3) | 24 (2.7) | |
| Physical activity | .896 | |||
| ȃNo physical activity | 410 (15.2) | 278 (15.4) | 132 (15) | |
| ȃPartial physical activity | 1408 (52.4) | 939 (52) | 469 (53.2) | |
| ȃComplete physical activity | 849 (31.6) | 574 (31.8) | 275 (31.2) | |
| ȃPrefer not to answer | 22 (0.8) | 16 (0.9) | 6 (0.7) | |
| Vaccination | <.001 | |||
| ȃNo vaccination | 397 (14.8) | 287 (15.9) | 110 (12.5) | |
| ȃ1 dose | 151 (5.6) | 107 (5.9) | 44 (5.0) | |
| ȃFully vaccinated (2–3 doses) | 2031 (75.5) | 1338 (74.0) | 693 (78.6) | |
| ȃPrefer not to answer | 21 (0.8) | 15 (0.8) | 6 (0.7) | |
| ȃNo information | 89 (3.3) | 60 (3.3) | 29 (3.3) | |
| Self-rated health at time of testing | .012 | |||
| ȃPoor | 237 (8.8) | 142 (7.9) | 95 (10.8) | |
| ȃGood | 2452 (91.2) | 1665 (92.1) | 787 (89.2) | |
| Comorbidities | ||||
| ȃObesity or overweight | 338 (12.6) | 231 (12.8) | 107 (12.1) | .621 |
| ȃHypertension | 159 (5.9) | 99 (5.5) | 60 (6.8) | .175 |
| ȃDiabetes | 44 (1.6) | 29 (1.6) | 15 (1.7) | .858 |
| ȃRespiratory disease | 114 (4.2) | 74 (4.1) | 40 (4.5) | .601 |
| ȃCardiovascular disease | 43 (1.6) | 23 (1.3) | 20 (2.3) | .054 |
| ȃHeadache disorders | 288 (10.7) | 177 (9.8) | 111 (12.6) | .029 |
| ȃSleep disorders | 250 (9.3) | 167 (9.2) | 83 (9.4) | .898 |
| ȃCognitive disorders | 155 (5.8) | 104 (5.8) | 51 (5.8) | .986 |
| ȃHyperthyroidism | 13 (0.5) | 5 (0.3) | 8 (0.9) | .027 |
| ȃHypothyroidism | 56 (2.1) | 36 (2) | 20 (2.3) | .643 |
| ȃDepression | 126 (4.7) | 76 (4.2) | 50 (5.7) | .094 |
| ȃAnxiety | 186 (6.9) | 127 (7) | 59 (6.7) | .737 |
| ȃRheumatological disorders | 168 (6.2) | 110 (6.1) | 58 (6.6) | .631 |
| ȃAnemia | 79 (2.9) | 50 (2.8) | 29 (3.3) | .457 |
| ȃChronic pain or fibromyalgia | 32 (1.2) | 20 (1.1) | 12 (1.4) | .572 |
| ȃIrritable bowel syndrome | 107 (4) | 63 (3.5) | 44 (5) | .063 |
Data are presented as no. (%). Abbreviation: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Prevalence of Post-COVID Symptoms at 12 Weeks
Overall, 11.7% of individuals infected by Omicron had symptoms 12 weeks after their infection (18.1% in nonvaccinated, 9.7% in vaccinated) compared to 10.4% of individuals who tested negative during the same period (P < .001). Prevalence estimates showed insomnia in 2.4% of Omicron cases compared to 2.1% of negative controls (P = .005), loss or change in smell in 3.5% of Omicron cases compared to 2.7% of negative controls (P < .001), and loss or change in taste in 2.6% of Omicron cases compared to 2.2% of negative controls (P = .003). There was no significant difference in the prevalence of all other listed symptoms between the 2 groups. The adjusted prevalences of symptoms 12 weeks after Omicron infection (BA.1 and BA.2) compared with individuals tested negative during the same time period are presented in Figure 2 and Table 2. Overall, 10.7% of confirmed Omicron cases had symptoms 12 weeks after their infection in the subgroup analysis, excluding potential infections with the Delta variant. When considering this subgroup analysis, results showed a difference in the prevalence of fatigue and chest pain between confirmed Omicron cases and negative controls.
Adjusted prevalence of post-COVID symptoms after Omicron infection (BA.1 and BA.2) in vaccinated and nonvaccinated individuals. *Any symptom is defined as the presence of 1 or more of the symptoms listed. Only symptoms with a new onset after the test date were taken into consideration. No vaccination is defined as individuals having received no vaccination or incomplete vaccination (1 dose). Individuals having preferred not to answer the vaccination status question were excluded from the subanalysis. Prevalence was adjusted for age, sex, vaccination status, monoclonal antibody treatment during the acute phase (casirivimab/imdevimab or sotrovimab; n = 15), time from infection, and the following pre-existing comorbidities: obesity or overweight, hypertension, diabetes, respiratory disease, cardiovascular disease, headache disorders, cognitive disorders, sleep disorders, depression, anxiety, hypothyroidism, rheumatologic disease, anemia, chronic pain or fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome. Abbreviation: COVID, coronavirus disease.
Adjusted Prevalence of Symptoms in Individuals Who Tested Positive for Omicron Infection Compared With Negative Controls, With Subanalysis Based on Vaccination Status and Subanalysis With Confirmatory Sequencing
| Omicron Variant BA.1/BA.2 | Subanalysis With Vaccination Status in SARS-CoV-2–Positive Individualsa | Subanalysis in Nonvaccinated Individuals Only | Subanalysis With Confirmed Sequencing Only, Omicron Variant BA.1/BA.2b | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SARS-CoV-2 Positive (n = 1807) | SARS-CoV-2 Negative (n = 882) | P | Vaccinated (n = 1338) | Nonvaccinated (n = 394) | P | SARS-CoV-2 Positive (n = 394) | SARS-CoV-2 Negative (n = 229) | P | SARS-CoV-2 Positive (n = 771) | SARS-CoV-2 Negative (n = 882) | P | |
| Any symptomc | 11.7 (11.4–12.0) | 10.4 (9.9–10.8) | <.001 | 9.7 (9.5–10.0) | 18.1 (17.5–18.8) | <.001 | 17.8 (17.1–18.4) | 18.9 (17.6–20.1) | .100 | 10.7 (10.2–11.2) | 10.4 (9.9–10.8) | .002 |
| Fatigue | 7.6 (7.4–7.8) | 7.3 (6.9–7.7) | .145 | 6.4 (6.2–6.6) | 11.9 (11.3–12.4) | <.001 | 10.8 (10.2–11.3) | 12.3 (11.2–13.3) | .005 | 6.0 (5.6–6.3) | 7.3 (6.9–7.7) | .027 |
| Concentration | 3.3 (3.2–3.4) | 3.4 (3.2–3.7) | .320 | 2.9 (2.8–3.0) | 4.7 (4.3–5.0) | <.001 | 4.6 (4.3–5.0) | 5.3 (4.7–5.9) | .032 | 3.4 (3.1–3.8) | 3.4 (3.2–3.7) | .360 |
| Headache | 4.0 (3.8–4.1) | 4.0 (3.7–4.2) | .922 | 3.5 (3.3–3.6) | 5.9 (5.4–6.3) | <.001 | 5.6 (5.2–6.1) | 6.9 (6.0–7.8) | .003 | 3.6 (3.2–4.0) | 4.0 (3.7–4.2) | .062 |
| Insomnia | 2.4 (2.2–2.5) | 2.1 (1.9–2.2) | .005 | 2.0 (1.9–2.1) | 3.4 (3.1–3.8) | <.001 | 3.4 (3.1–3.7) | 3.9 (3.4–4.5) | .045 | 2.3 (1.9–2.7) | 2.1 (1.9–2.2) | .174 |
| Smell | 3.5 (3.3–3.7) | 2.7 (2.4–3.0) | <.001 | 2.4 (2.2–2.5) | 7.6 (7.0–8.2) | <.001 | 8.2 (7.7–8.8) | 8.7 (7.9–9.6) | .310 | 3.6 (2.9–4.4) | 2.7 (2.4–3.0) | .119 |
| Taste | 2.6 (2.5–2.8) | 2.2 (1.9–2.4) | .003 | 1.6 (1.5–1.7) | 6.3 (5.7–6.8) | <.001 | 6.5 (6.0–6.9) | 7.1 (6.4–7.7) | .168 | 2.5 (2.0–3.0) | 2.2 (1.9–2.4) | .330 |
| Dyspnea | 2.8 (2.7–2.9) | 2.7 (2.5–2.9) | .323 | 2.3 (2.2–2.4) | 4.6 (4.3–4.9) | <.001 | 4.3 (4.0–4.6) | 4.9 (4.3–5.5) | .043 | 2.9 (2.6–3.2) | 2.7 (2.5–2.9) | .115 |
| Cough | 2.9 (2.8–2.9) | 2.9 (2.8–3.0) | .656 | 2.7 (2.6–2.7) | 3.5 (3.3–3.7) | <.001 | 3.2 (3.0–3.3) | 3.5 (3.2–3.8) | .031 | 3.0 (2.7–3.2) | 2.9 (2.8–3.0) | .771 |
| Myalgia | 2.5 (2.4–2.6) | 2.1 (1.9–2.3) | .403 | 2.3 (2.2–2.4) | 2.9 (2.6–3.1) | <.001 | 2.7 (2.5–2.9) | 3.5 (2.9–4.1) | .001 | 2.5 (2.1–2.8) | 2.1 (1.9–2.3) | .433 |
| Arthralgia | 1.8 (1.6–1.9) | 1.9 (1.6–2.1) | .457 | 1.5 (1.4–1.6) | 2.8 (2.5–3.0) | <.001 | 2.6 (2.4–2.8) | 3.5 (2.9–4.0) | .001 | 2.3 (1.9–2.7) | 1.9 (1.6–2.1) | .294 |
| Paresthesia | 2.0 (1.9–2.1) | 1.9 (1.8–2.0) | .179 | 1.7 (1.7–1.8) | 2.9 (2.7–3.1) | <.001 | 2.9 (2.7–3.1) | 3.5 (3.1–4.0) | .002 | 2.6 (2.1–3.1) | 1.9 (1.8–2.0) | .135 |
| Chest pain | 1.1 (1.1–1.2) | 1.0 (0.9–1.2) | .133 | 0.9 (0.8–1.0) | 1.9 (1.7–2.1) | <.001 | 1.7 (1.6–1.9) | 1.8 (1.6–2.1) | .495 | 2.3 (1.8–2.9) | 1.0 (0.9–1.2) | .038 |
| Palpitations | 1.1 (1.0–1.2) | 1.1 (1.0–1.2) | .693 | 0.9 (0.9–1.0) | 1.6 (1.4–1.8) | <.001 | 1.3 (1.1–1.5) | 1.6 (1.2–1.9) | .162 | 1.6 (1.2–1.9) | 1.1 (1.0–1.2) | .395 |
| Digestive | 1.6 (1.5–1.6) | 1.7 (1.5–1.8) | .219 | 1.4 (1.4–1.5) | 1.9 (1.7–2.1) | <.001 | 2.0 (1.8–2.2) | 2.5 (2.1–2.8) | .007 | 1.8 (1.6–2.1) | 1.7 (1.5–1.8) | .873 |
| Hair loss | 0.8 (0.7–0.9) | 0.7 (0.6–0.8) | .070 | 0.6 (0.5–0.7) | 1.5 (1.2–1.9) | <.001 | 1.2 (1.1–1.3) | 1.5 (1.2–1.9) | .024 | 1.1 (0.7–1.5) | 0.7 (0.6–0.8) | .485 |
| Omicron Variant BA.1/BA.2 | Subanalysis With Vaccination Status in SARS-CoV-2–Positive Individualsa | Subanalysis in Nonvaccinated Individuals Only | Subanalysis With Confirmed Sequencing Only, Omicron Variant BA.1/BA.2b | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SARS-CoV-2 Positive (n = 1807) | SARS-CoV-2 Negative (n = 882) | P | Vaccinated (n = 1338) | Nonvaccinated (n = 394) | P | SARS-CoV-2 Positive (n = 394) | SARS-CoV-2 Negative (n = 229) | P | SARS-CoV-2 Positive (n = 771) | SARS-CoV-2 Negative (n = 882) | P | |
| Any symptomc | 11.7 (11.4–12.0) | 10.4 (9.9–10.8) | <.001 | 9.7 (9.5–10.0) | 18.1 (17.5–18.8) | <.001 | 17.8 (17.1–18.4) | 18.9 (17.6–20.1) | .100 | 10.7 (10.2–11.2) | 10.4 (9.9–10.8) | .002 |
| Fatigue | 7.6 (7.4–7.8) | 7.3 (6.9–7.7) | .145 | 6.4 (6.2–6.6) | 11.9 (11.3–12.4) | <.001 | 10.8 (10.2–11.3) | 12.3 (11.2–13.3) | .005 | 6.0 (5.6–6.3) | 7.3 (6.9–7.7) | .027 |
| Concentration | 3.3 (3.2–3.4) | 3.4 (3.2–3.7) | .320 | 2.9 (2.8–3.0) | 4.7 (4.3–5.0) | <.001 | 4.6 (4.3–5.0) | 5.3 (4.7–5.9) | .032 | 3.4 (3.1–3.8) | 3.4 (3.2–3.7) | .360 |
| Headache | 4.0 (3.8–4.1) | 4.0 (3.7–4.2) | .922 | 3.5 (3.3–3.6) | 5.9 (5.4–6.3) | <.001 | 5.6 (5.2–6.1) | 6.9 (6.0–7.8) | .003 | 3.6 (3.2–4.0) | 4.0 (3.7–4.2) | .062 |
| Insomnia | 2.4 (2.2–2.5) | 2.1 (1.9–2.2) | .005 | 2.0 (1.9–2.1) | 3.4 (3.1–3.8) | <.001 | 3.4 (3.1–3.7) | 3.9 (3.4–4.5) | .045 | 2.3 (1.9–2.7) | 2.1 (1.9–2.2) | .174 |
| Smell | 3.5 (3.3–3.7) | 2.7 (2.4–3.0) | <.001 | 2.4 (2.2–2.5) | 7.6 (7.0–8.2) | <.001 | 8.2 (7.7–8.8) | 8.7 (7.9–9.6) | .310 | 3.6 (2.9–4.4) | 2.7 (2.4–3.0) | .119 |
| Taste | 2.6 (2.5–2.8) | 2.2 (1.9–2.4) | .003 | 1.6 (1.5–1.7) | 6.3 (5.7–6.8) | <.001 | 6.5 (6.0–6.9) | 7.1 (6.4–7.7) | .168 | 2.5 (2.0–3.0) | 2.2 (1.9–2.4) | .330 |
| Dyspnea | 2.8 (2.7–2.9) | 2.7 (2.5–2.9) | .323 | 2.3 (2.2–2.4) | 4.6 (4.3–4.9) | <.001 | 4.3 (4.0–4.6) | 4.9 (4.3–5.5) | .043 | 2.9 (2.6–3.2) | 2.7 (2.5–2.9) | .115 |
| Cough | 2.9 (2.8–2.9) | 2.9 (2.8–3.0) | .656 | 2.7 (2.6–2.7) | 3.5 (3.3–3.7) | <.001 | 3.2 (3.0–3.3) | 3.5 (3.2–3.8) | .031 | 3.0 (2.7–3.2) | 2.9 (2.8–3.0) | .771 |
| Myalgia | 2.5 (2.4–2.6) | 2.1 (1.9–2.3) | .403 | 2.3 (2.2–2.4) | 2.9 (2.6–3.1) | <.001 | 2.7 (2.5–2.9) | 3.5 (2.9–4.1) | .001 | 2.5 (2.1–2.8) | 2.1 (1.9–2.3) | .433 |
| Arthralgia | 1.8 (1.6–1.9) | 1.9 (1.6–2.1) | .457 | 1.5 (1.4–1.6) | 2.8 (2.5–3.0) | <.001 | 2.6 (2.4–2.8) | 3.5 (2.9–4.0) | .001 | 2.3 (1.9–2.7) | 1.9 (1.6–2.1) | .294 |
| Paresthesia | 2.0 (1.9–2.1) | 1.9 (1.8–2.0) | .179 | 1.7 (1.7–1.8) | 2.9 (2.7–3.1) | <.001 | 2.9 (2.7–3.1) | 3.5 (3.1–4.0) | .002 | 2.6 (2.1–3.1) | 1.9 (1.8–2.0) | .135 |
| Chest pain | 1.1 (1.1–1.2) | 1.0 (0.9–1.2) | .133 | 0.9 (0.8–1.0) | 1.9 (1.7–2.1) | <.001 | 1.7 (1.6–1.9) | 1.8 (1.6–2.1) | .495 | 2.3 (1.8–2.9) | 1.0 (0.9–1.2) | .038 |
| Palpitations | 1.1 (1.0–1.2) | 1.1 (1.0–1.2) | .693 | 0.9 (0.9–1.0) | 1.6 (1.4–1.8) | <.001 | 1.3 (1.1–1.5) | 1.6 (1.2–1.9) | .162 | 1.6 (1.2–1.9) | 1.1 (1.0–1.2) | .395 |
| Digestive | 1.6 (1.5–1.6) | 1.7 (1.5–1.8) | .219 | 1.4 (1.4–1.5) | 1.9 (1.7–2.1) | <.001 | 2.0 (1.8–2.2) | 2.5 (2.1–2.8) | .007 | 1.8 (1.6–2.1) | 1.7 (1.5–1.8) | .873 |
| Hair loss | 0.8 (0.7–0.9) | 0.7 (0.6–0.8) | .070 | 0.6 (0.5–0.7) | 1.5 (1.2–1.9) | <.001 | 1.2 (1.1–1.3) | 1.5 (1.2–1.9) | .024 | 1.1 (0.7–1.5) | 0.7 (0.6–0.8) | .485 |
Data in parentheses is 95% confidence interval. Prevalence-adjusted age, sex, vaccination status, monoclonal antibody treatment during the acute phase (casirivimab/imdevimab or sotrovimab; n = 15), time from infection, and the following pre-existing comorbidities: obesity or overweight, hypertension, diabetes, respiratory disease, cardiovascular disease, headache disorders, cognitive disorders, sleep disorders, depression, anxiety, hypothyroidism, rheumatologic disease, anemia, chronic pain or fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome. Abbreviation: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Nonvaccinated status is defined as individuals having received no vaccination or incomplete vaccination (1 dose). Individuals who preferred not to answer the vaccination status question were excluded from the subanalysis.
Only individuals who tested positive with confirmed sequencing of Omicron infection were included if tested between 17 December 2022 and 16 January 2022. Individuals who tested positive between 17 January 2022 and 13 February 2022 were all considered to have Omicron infection and were included, corresponding to the pandemic phase in Geneva at the time.
Any symptom is defined as the presence of ≥1 of the symptoms listed. Only symptoms with a new onset after the test date were taken into consideration.
Adjusted Prevalence of Symptoms in Individuals Who Tested Positive for Omicron Infection Compared With Negative Controls, With Subanalysis Based on Vaccination Status and Subanalysis With Confirmatory Sequencing
| Omicron Variant BA.1/BA.2 | Subanalysis With Vaccination Status in SARS-CoV-2–Positive Individualsa | Subanalysis in Nonvaccinated Individuals Only | Subanalysis With Confirmed Sequencing Only, Omicron Variant BA.1/BA.2b | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SARS-CoV-2 Positive (n = 1807) | SARS-CoV-2 Negative (n = 882) | P | Vaccinated (n = 1338) | Nonvaccinated (n = 394) | P | SARS-CoV-2 Positive (n = 394) | SARS-CoV-2 Negative (n = 229) | P | SARS-CoV-2 Positive (n = 771) | SARS-CoV-2 Negative (n = 882) | P | |
| Any symptomc | 11.7 (11.4–12.0) | 10.4 (9.9–10.8) | <.001 | 9.7 (9.5–10.0) | 18.1 (17.5–18.8) | <.001 | 17.8 (17.1–18.4) | 18.9 (17.6–20.1) | .100 | 10.7 (10.2–11.2) | 10.4 (9.9–10.8) | .002 |
| Fatigue | 7.6 (7.4–7.8) | 7.3 (6.9–7.7) | .145 | 6.4 (6.2–6.6) | 11.9 (11.3–12.4) | <.001 | 10.8 (10.2–11.3) | 12.3 (11.2–13.3) | .005 | 6.0 (5.6–6.3) | 7.3 (6.9–7.7) | .027 |
| Concentration | 3.3 (3.2–3.4) | 3.4 (3.2–3.7) | .320 | 2.9 (2.8–3.0) | 4.7 (4.3–5.0) | <.001 | 4.6 (4.3–5.0) | 5.3 (4.7–5.9) | .032 | 3.4 (3.1–3.8) | 3.4 (3.2–3.7) | .360 |
| Headache | 4.0 (3.8–4.1) | 4.0 (3.7–4.2) | .922 | 3.5 (3.3–3.6) | 5.9 (5.4–6.3) | <.001 | 5.6 (5.2–6.1) | 6.9 (6.0–7.8) | .003 | 3.6 (3.2–4.0) | 4.0 (3.7–4.2) | .062 |
| Insomnia | 2.4 (2.2–2.5) | 2.1 (1.9–2.2) | .005 | 2.0 (1.9–2.1) | 3.4 (3.1–3.8) | <.001 | 3.4 (3.1–3.7) | 3.9 (3.4–4.5) | .045 | 2.3 (1.9–2.7) | 2.1 (1.9–2.2) | .174 |
| Smell | 3.5 (3.3–3.7) | 2.7 (2.4–3.0) | <.001 | 2.4 (2.2–2.5) | 7.6 (7.0–8.2) | <.001 | 8.2 (7.7–8.8) | 8.7 (7.9–9.6) | .310 | 3.6 (2.9–4.4) | 2.7 (2.4–3.0) | .119 |
| Taste | 2.6 (2.5–2.8) | 2.2 (1.9–2.4) | .003 | 1.6 (1.5–1.7) | 6.3 (5.7–6.8) | <.001 | 6.5 (6.0–6.9) | 7.1 (6.4–7.7) | .168 | 2.5 (2.0–3.0) | 2.2 (1.9–2.4) | .330 |
| Dyspnea | 2.8 (2.7–2.9) | 2.7 (2.5–2.9) | .323 | 2.3 (2.2–2.4) | 4.6 (4.3–4.9) | <.001 | 4.3 (4.0–4.6) | 4.9 (4.3–5.5) | .043 | 2.9 (2.6–3.2) | 2.7 (2.5–2.9) | .115 |
| Cough | 2.9 (2.8–2.9) | 2.9 (2.8–3.0) | .656 | 2.7 (2.6–2.7) | 3.5 (3.3–3.7) | <.001 | 3.2 (3.0–3.3) | 3.5 (3.2–3.8) | .031 | 3.0 (2.7–3.2) | 2.9 (2.8–3.0) | .771 |
| Myalgia | 2.5 (2.4–2.6) | 2.1 (1.9–2.3) | .403 | 2.3 (2.2–2.4) | 2.9 (2.6–3.1) | <.001 | 2.7 (2.5–2.9) | 3.5 (2.9–4.1) | .001 | 2.5 (2.1–2.8) | 2.1 (1.9–2.3) | .433 |
| Arthralgia | 1.8 (1.6–1.9) | 1.9 (1.6–2.1) | .457 | 1.5 (1.4–1.6) | 2.8 (2.5–3.0) | <.001 | 2.6 (2.4–2.8) | 3.5 (2.9–4.0) | .001 | 2.3 (1.9–2.7) | 1.9 (1.6–2.1) | .294 |
| Paresthesia | 2.0 (1.9–2.1) | 1.9 (1.8–2.0) | .179 | 1.7 (1.7–1.8) | 2.9 (2.7–3.1) | <.001 | 2.9 (2.7–3.1) | 3.5 (3.1–4.0) | .002 | 2.6 (2.1–3.1) | 1.9 (1.8–2.0) | .135 |
| Chest pain | 1.1 (1.1–1.2) | 1.0 (0.9–1.2) | .133 | 0.9 (0.8–1.0) | 1.9 (1.7–2.1) | <.001 | 1.7 (1.6–1.9) | 1.8 (1.6–2.1) | .495 | 2.3 (1.8–2.9) | 1.0 (0.9–1.2) | .038 |
| Palpitations | 1.1 (1.0–1.2) | 1.1 (1.0–1.2) | .693 | 0.9 (0.9–1.0) | 1.6 (1.4–1.8) | <.001 | 1.3 (1.1–1.5) | 1.6 (1.2–1.9) | .162 | 1.6 (1.2–1.9) | 1.1 (1.0–1.2) | .395 |
| Digestive | 1.6 (1.5–1.6) | 1.7 (1.5–1.8) | .219 | 1.4 (1.4–1.5) | 1.9 (1.7–2.1) | <.001 | 2.0 (1.8–2.2) | 2.5 (2.1–2.8) | .007 | 1.8 (1.6–2.1) | 1.7 (1.5–1.8) | .873 |
| Hair loss | 0.8 (0.7–0.9) | 0.7 (0.6–0.8) | .070 | 0.6 (0.5–0.7) | 1.5 (1.2–1.9) | <.001 | 1.2 (1.1–1.3) | 1.5 (1.2–1.9) | .024 | 1.1 (0.7–1.5) | 0.7 (0.6–0.8) | .485 |
| Omicron Variant BA.1/BA.2 | Subanalysis With Vaccination Status in SARS-CoV-2–Positive Individualsa | Subanalysis in Nonvaccinated Individuals Only | Subanalysis With Confirmed Sequencing Only, Omicron Variant BA.1/BA.2b | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SARS-CoV-2 Positive (n = 1807) | SARS-CoV-2 Negative (n = 882) | P | Vaccinated (n = 1338) | Nonvaccinated (n = 394) | P | SARS-CoV-2 Positive (n = 394) | SARS-CoV-2 Negative (n = 229) | P | SARS-CoV-2 Positive (n = 771) | SARS-CoV-2 Negative (n = 882) | P | |
| Any symptomc | 11.7 (11.4–12.0) | 10.4 (9.9–10.8) | <.001 | 9.7 (9.5–10.0) | 18.1 (17.5–18.8) | <.001 | 17.8 (17.1–18.4) | 18.9 (17.6–20.1) | .100 | 10.7 (10.2–11.2) | 10.4 (9.9–10.8) | .002 |
| Fatigue | 7.6 (7.4–7.8) | 7.3 (6.9–7.7) | .145 | 6.4 (6.2–6.6) | 11.9 (11.3–12.4) | <.001 | 10.8 (10.2–11.3) | 12.3 (11.2–13.3) | .005 | 6.0 (5.6–6.3) | 7.3 (6.9–7.7) | .027 |
| Concentration | 3.3 (3.2–3.4) | 3.4 (3.2–3.7) | .320 | 2.9 (2.8–3.0) | 4.7 (4.3–5.0) | <.001 | 4.6 (4.3–5.0) | 5.3 (4.7–5.9) | .032 | 3.4 (3.1–3.8) | 3.4 (3.2–3.7) | .360 |
| Headache | 4.0 (3.8–4.1) | 4.0 (3.7–4.2) | .922 | 3.5 (3.3–3.6) | 5.9 (5.4–6.3) | <.001 | 5.6 (5.2–6.1) | 6.9 (6.0–7.8) | .003 | 3.6 (3.2–4.0) | 4.0 (3.7–4.2) | .062 |
| Insomnia | 2.4 (2.2–2.5) | 2.1 (1.9–2.2) | .005 | 2.0 (1.9–2.1) | 3.4 (3.1–3.8) | <.001 | 3.4 (3.1–3.7) | 3.9 (3.4–4.5) | .045 | 2.3 (1.9–2.7) | 2.1 (1.9–2.2) | .174 |
| Smell | 3.5 (3.3–3.7) | 2.7 (2.4–3.0) | <.001 | 2.4 (2.2–2.5) | 7.6 (7.0–8.2) | <.001 | 8.2 (7.7–8.8) | 8.7 (7.9–9.6) | .310 | 3.6 (2.9–4.4) | 2.7 (2.4–3.0) | .119 |
| Taste | 2.6 (2.5–2.8) | 2.2 (1.9–2.4) | .003 | 1.6 (1.5–1.7) | 6.3 (5.7–6.8) | <.001 | 6.5 (6.0–6.9) | 7.1 (6.4–7.7) | .168 | 2.5 (2.0–3.0) | 2.2 (1.9–2.4) | .330 |
| Dyspnea | 2.8 (2.7–2.9) | 2.7 (2.5–2.9) | .323 | 2.3 (2.2–2.4) | 4.6 (4.3–4.9) | <.001 | 4.3 (4.0–4.6) | 4.9 (4.3–5.5) | .043 | 2.9 (2.6–3.2) | 2.7 (2.5–2.9) | .115 |
| Cough | 2.9 (2.8–2.9) | 2.9 (2.8–3.0) | .656 | 2.7 (2.6–2.7) | 3.5 (3.3–3.7) | <.001 | 3.2 (3.0–3.3) | 3.5 (3.2–3.8) | .031 | 3.0 (2.7–3.2) | 2.9 (2.8–3.0) | .771 |
| Myalgia | 2.5 (2.4–2.6) | 2.1 (1.9–2.3) | .403 | 2.3 (2.2–2.4) | 2.9 (2.6–3.1) | <.001 | 2.7 (2.5–2.9) | 3.5 (2.9–4.1) | .001 | 2.5 (2.1–2.8) | 2.1 (1.9–2.3) | .433 |
| Arthralgia | 1.8 (1.6–1.9) | 1.9 (1.6–2.1) | .457 | 1.5 (1.4–1.6) | 2.8 (2.5–3.0) | <.001 | 2.6 (2.4–2.8) | 3.5 (2.9–4.0) | .001 | 2.3 (1.9–2.7) | 1.9 (1.6–2.1) | .294 |
| Paresthesia | 2.0 (1.9–2.1) | 1.9 (1.8–2.0) | .179 | 1.7 (1.7–1.8) | 2.9 (2.7–3.1) | <.001 | 2.9 (2.7–3.1) | 3.5 (3.1–4.0) | .002 | 2.6 (2.1–3.1) | 1.9 (1.8–2.0) | .135 |
| Chest pain | 1.1 (1.1–1.2) | 1.0 (0.9–1.2) | .133 | 0.9 (0.8–1.0) | 1.9 (1.7–2.1) | <.001 | 1.7 (1.6–1.9) | 1.8 (1.6–2.1) | .495 | 2.3 (1.8–2.9) | 1.0 (0.9–1.2) | .038 |
| Palpitations | 1.1 (1.0–1.2) | 1.1 (1.0–1.2) | .693 | 0.9 (0.9–1.0) | 1.6 (1.4–1.8) | <.001 | 1.3 (1.1–1.5) | 1.6 (1.2–1.9) | .162 | 1.6 (1.2–1.9) | 1.1 (1.0–1.2) | .395 |
| Digestive | 1.6 (1.5–1.6) | 1.7 (1.5–1.8) | .219 | 1.4 (1.4–1.5) | 1.9 (1.7–2.1) | <.001 | 2.0 (1.8–2.2) | 2.5 (2.1–2.8) | .007 | 1.8 (1.6–2.1) | 1.7 (1.5–1.8) | .873 |
| Hair loss | 0.8 (0.7–0.9) | 0.7 (0.6–0.8) | .070 | 0.6 (0.5–0.7) | 1.5 (1.2–1.9) | <.001 | 1.2 (1.1–1.3) | 1.5 (1.2–1.9) | .024 | 1.1 (0.7–1.5) | 0.7 (0.6–0.8) | .485 |
Data in parentheses is 95% confidence interval. Prevalence-adjusted age, sex, vaccination status, monoclonal antibody treatment during the acute phase (casirivimab/imdevimab or sotrovimab; n = 15), time from infection, and the following pre-existing comorbidities: obesity or overweight, hypertension, diabetes, respiratory disease, cardiovascular disease, headache disorders, cognitive disorders, sleep disorders, depression, anxiety, hypothyroidism, rheumatologic disease, anemia, chronic pain or fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome. Abbreviation: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Nonvaccinated status is defined as individuals having received no vaccination or incomplete vaccination (1 dose). Individuals who preferred not to answer the vaccination status question were excluded from the subanalysis.
Only individuals who tested positive with confirmed sequencing of Omicron infection were included if tested between 17 December 2022 and 16 January 2022. Individuals who tested positive between 17 January 2022 and 13 February 2022 were all considered to have Omicron infection and were included, corresponding to the pandemic phase in Geneva at the time.
Any symptom is defined as the presence of ≥1 of the symptoms listed. Only symptoms with a new onset after the test date were taken into consideration.
In a subgroup analysis of only individuals reporting that their symptoms worsened and persisted for more than 12 weeks since the test date (n = 123), the prevalence of symptoms was 15.5% (95% confidence interval [CI]: 13.7–17.4%) in SARS-CoV-2–positive individuals (20.4% in nonvaccinated, 12.4% in vaccinated) compared to 14.0% (95% CI: 11.2–16.8%) in SARS-CoV-2–negative individuals (20.7% in nonvaccinated, 9.9% in vaccinated) (P = .358).
Individuals reported functional impairment in 19.4% (95% CI: 18.9–19.9%) of Omicron cases (BA.1 and BA.2) compared to 20.6% (95% CI: 20.0–21.3%) in negative controls. Using univariate and multivariable logistic regression models, there was no association between Omicron infection and functional impairment (odd ratio [OR]: 1.12 [95% CI: .83–1.48]; and aOR: 1.14 [95% CI: .83–1.55]) compared with negative controls.
Association Between Vaccination Status and Post-COVID Symptoms
A subgroup analysis evaluated the prevalence of symptoms in vaccinated Omicron cases (BA.1 and BA.2) compared with nonvaccinated Omicron cases (BA.1 and BA.2) and is shown in Table 2. Overall, 9.7% of vaccinated Omicron cases had symptoms at 12 weeks compared to 18.1% of nonvaccinated cases (P < .001). Fatigue was present in 6.4% of vaccinated cases compared to 11.9% of nonvaccinated cases (P < .001). Difficulty concentrating, headache, insomnia, loss or change in smell, loss or change in taste, dyspnea, cough, myalgia, arthralgia, paresthesia, chest pain, palpitations, digestive symptoms, and hair loss were all significantly less prevalent in vaccinated Omicron cases compared with nonvaccinated cases. When considering baseline characteristics between vaccinated and nonvaccinated individuals, more vaccinated individuals were in the 60-years-and-above age category, married, living with a partner or other people, retired, and nonsmokers, or had pre-existing hypertension (Supplementary Table 2).
The overall prevalence of post-COVID condition was not significantly different between Omicron cases and SARS-CoV-2 negative individuals in the non-vaccinated subgroup (17.6% compared to 18.9%, P = 0.100). However, some of the individually listed symptoms had a higher prevalence in the non-vaccinated SARS-CoV-2 negative subgroup compared to non-vaccinated Omicron cases (Table 2, Figure 2).
DISCUSSION
One-tenth (11.7%) of individuals had persistent symptoms 12 weeks after an infection by Omicron variants (BA.1 and BA.2). The prevalence in infected individuals was overall comparable to the negative controls, with 10.4% of this latter group reporting symptoms similar to post-COVID condition. A subgroup analysis showed a significantly higher prevalence of symptoms in nonvaccinated individuals.
Studies had shown a prevalence of post-COVID symptoms in 26% [4] to 39% [13] of outpatient individuals infected by previous variants. A study in the same source population in Geneva, Switzerland, showed a prevalence of post-COVID symptoms in 33% [1] of individuals, 12 months after their infection (infection date between March and July 2020). While the risk of post-COVID symptoms is lower after Omicron infection (BA.1 and BA.2) compared with previous variants [12], this study shows that 18.1% of nonvaccinated individuals still reported symptoms after Omicron infection, with significant differences in the prevalence of symptoms between vaccinated and nonvaccinated Omicron cases (BA.1 and BA.2). Baseline characteristics showed that older individuals (retired, living with a partner or other people, married), nonsmokers, individuals with pre-existing hypertension, and individuals with a higher educational level were more prone towards vaccination (Supplementary Material 2). These results confirm previous studies in Geneva showing that younger individuals were less inclined to be vaccinated [26]. Symptoms were still less prevalent in vaccinated individuals even if older and with potentially more comorbidities, further underlining the importance of vaccination. Vaccination decreases the viral load and the length of shedding [24], and plays an important role in the acute and postacute phases of the disease, despite escape mutations in new variants and a decrease in protection with time since the last vaccination dose [27]. The lower prevalence of persistent symptoms after Omicron infection (BA.1 and BA.2) could also potentially be associated with the less symptomatic acute presentation of the disease [28]. Previous studies have shown that the number of symptoms in the acute phase is positively associated with the persistence of symptoms over the long term [28]. There was also no association between Omicron cases and functional impairment compared with negative controls, correlating with the overall lower prevalence of post-COVID symptoms.
The present study complements initial findings of the prevalence of persistent symptoms after Omicron infection [12], showing results at 12 weeks after infection as defined by the World Health Organization [2]. An overall lower prevalence of post-COVID condition including less persistent symptoms and functional impairment is seen at 12 weeks compared with previous variants, with a similar prevalence of persistent symptoms in infected individuals compared with negative controls during the same time period. While a decreased prevalence of post-COVID conditions after Omicron infection (BA.1 and BA.2) could be reassuring, caution should be taken considering the impact of vaccination, as well as the emergence of new variants. Additionally, even though most Omicron cases occur in outpatient settings, underlining the importance of the present results, a recent communication showed a high prevalence of post-COVID symptoms in hospitalized individuals [13], with up to 76% reporting symptoms 4–12 weeks after the infection. Of note, this study also showed a high prevalence of symptoms in SARS-CoV-2–negative individuals in vaccinated and nonvaccinated individuals. This prevalence can be potentially explained by the toll of the pandemic in general, with previous studies showing a prevalence of symptoms in SARS-CoV-2–negative individuals [1] in the same source population in Geneva. There was also a difference in the prevalence of symptoms in the vaccinated compared with nonvaccinated individuals in the control group. The overall prevalence of symptoms in the control group and the difference between the vaccinated and nonvaccinated individuals could also be explained by potential false-negative results in the SARS-CoV-2–negative group [29], or infections that were not tested in the acute phase leading to post-COVID symptoms. Overall, vaccination seemed to protect against the prevalence of persistent symptoms.
Limitations include the potential false-negative RT-PCR tests. The decision to consider a negative RT-PCR test as negative for a SARS-CoV-2 infection was made to objectively assess the duration of symptoms and the impact of a SARS-CoV-2 infection independently of other potential factors that would be present in the Omicron cases and negative controls. This could have included some individuals with potential SARS-CoV-2 infection and a negative test result in the control group [29]. A response rate of 30% could also limit generalizability with a potential participation bias. The study cohort had a high proportion of individuals with a tertiary education, and when comparing available data, younger individuals and men were found to be less likely to participate in the study (62.5% of nonparticipants were aged ≤40 years compared to 47.0% of participants, and 46.6% of nonparticipants were men compared to 37.2% of participants). Limitations also include recall bias and the subjective nature of the self-reported symptoms, with a difficulty to attribute them directly to the virus versus the pandemic. Adjusting for several potentially confounding factors and taking into consideration new symptoms only, as well as comparing results with noninfected individuals, were some of the methods used for mitigation. Additionally, the small number of participants having received monoclonal antibody treatment in the acute phase (n = 15) does not allow for results to be drawn on their role in this context; however, the prevalence of symptoms was adjusted for this variable. Finally, this study explores post-COVID symptoms and not all potential postacute sequelae of SARS-CoV-2, which include an increased risk of cardiovascular, hematologic, gastrointestinal, kidney, mental health, metabolic, musculoskeletal, and neurologic disorders [30].
In conclusion, the differential prevalence of post-COVID symptoms and functional impairment attributable to Omicron BA.1 and BA.2 infection is low compared with negative controls, in contrast to data reported with prior variants. Vaccination is associated with a significantly lower prevalence of post-COVID symptoms following Omicron infection. While this study evaluated symptoms at 12 weeks, it will be important to do so at 6–12 months and beyond. Further investigations of the risk of post-COVID conditions following infections from newer variants and the impact of different treatments in the acute and postacute phases of infection are also warranted.
Supplementary Data
Supplementary materials are available at Clinical Infectious Diseases online. Consisting of data provided by the authors to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the authors, so questions or comments should be addressed to the corresponding author.
Notes
Data availability. Individual study data that underlie the results reported in this article can be made available to the scientific community after de-identification and upon submission of a data request application to the investigator board via the corresponding author.
Disclaimer. The funders of the study had no role in the study design, data collection, data analysis, data interpretation, or writing of the manuscript.
Financial support. This work was supported by the Leenaards Foundation and the Geneva University Hospitals Private Foundation.
References
Author notes
CoviCare Study Team members are listed in the Notes section.
Potential conflicts of interest. The authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
CoviCare Study Team. Mayssam Nehme, Pauline Vetter, Olivia Braillard, Frederic Assal, Frederic Lador, Ivan Guerreiro, Matteo Coen, Thomas Agoritsas, Jean-Luc Reny, Christophe Graf, Delphine S. Courvoisier, Lamyae Benzakour, Stéphane Genevay, Kim Lauper, Julien Salamun, Hervé Spechbach, Frederique Jacquerioz, Marwène Grira, Riccardo Favale, Guido Bondolfi, Aglaé Tardin, Paola M. Soccal, Dina Zekry, Silvia Stringhini, Philippe Meyer, Nana Kwabena Poku, Basile N. Landis, José Sandoval, Julien Ehrsam, Simon Regard, Camille Genecand, Garance Kopp, Gilles Allali, Samuel Cordey, Keith Harshman, Ioannis Xenarios, Lorenzo Cerutti, Cedric Howald, Henri Pegeot, Melyssa Elies, Deborah Penet, Pietro Cattaneo, Fosca Gattoni, Michael Bel, Damir Perisa, François Chappuis, Laurent Kaiser, Idris Guessous.
