Factors Associated With COVID-19 Non-Vaccination in Switzerland: A Nationwide Study.

Objectives: We compared socio-demographic characteristics, health-related variables, vaccination-related beliefs and attitudes, vaccination acceptance, and personality traits of individuals who vaccinated against COVID-19 and who did not vaccinate by December 2021. Methods: This cross-sectional study used data of 10,642 adult participants from the Corona Immunitas eCohort, an age-stratified random sample of the population of several cantons in Switzerland. We used multivariable logistic regression models to explore associations of vaccination status with socio-demographic, health, and behavioral factors. Results: Non-vaccinated individuals represented 12.4% of the sample. Compared to vaccinated individuals, non-vaccinated individuals were more likely to be younger, healthier, employed, have lower income, not worried about their health, have previously tested positive for SARS-CoV-2 infection, express lower vaccination acceptance, and/or report higher conscientiousness. Among non-vaccinated individuals, 19.9% and 21.3% had low confidence in the safety and effectiveness of SARS-CoV-2 vaccine, respectively. However, 29.1% and 26.7% of individuals with concerns about vaccine effectiveness and side effects at baseline, respectively vaccinated during the study period. Conclusion: In addition to known socio-demographic and health-related factors, non-vaccination was associated with concerns regarding vaccine safety and effectiveness.

COVID-19 Fears and Preventive Behaviors among Prison Staff

This study focused on COVID-19 preventive behaviors and fears among prison staff members after the first wave of the pandemic. Cross-sectional data from 171 participants were collected in Switzerland. The level of fears (58.5%) and protective behaviors (100%) were high. Correctional officers adhered less to preventive measures than other staff members (p = .001). Fears were related to a reduction of social contacts (p = .006) and worries about physical health was related to preventive behaviors in general (p = .006). There is a need to raise prison staff awareness regarding their vulnerability to the SARS-CoV-2 in order to improve the effectiveness of health campaigns in prison settings. Special attention should be given to correctional officers.

Perceptions of vaccination certificates among the general population in Geneva, Switzerland.

OBJECTIVE: This study aimed to assess the public perception of COVID-19 vaccination certificates as well as potential differences between individuals. METHODS: Between 17 March and 1 April 2021, a self-administered online questionnaire was proposed to all persons aged 18 years and older participating in the longitudinal follow-up of SARS-CoV-2 seroprevalence studies in Geneva, Switzerland. The questionnaire covered aspects of individual and collective benefits, and allowed participants to select contexts in which vaccination certificates should be presented. Results were presented as the proportion of persons agreeing or disagreeing with the implementation of vaccination certificates, selecting specific contexts where certificates should be presented, and agreeing or disagreeing with the potential risks related to certificates. Logistic regression was used to calculate odds ratios for factors associated with certificate non-acceptance. RESULTS: Overall, 4067 individuals completed the questionnaire (response rate 77.4%; mean age 53.3 ± standard deviation 14.4 years; 56.1% were women). About 61.0% of participants agreed or strongly agreed that a vaccination certificate was necessary in certain contexts and 21.6% believed there was no context where vaccination certificates should be presented. Contexts where a majority of participants perceived a vaccination certificate should be presented included jobs where others would be at risk of COVID-related complications (60.7%), jobs where employees would be at risk of getting infected (58.7%), or to be exempt from quarantine when travelling abroad (56.0%). Contexts where fewer individuals perceived the need for vaccination certificates to be presented were participation in large gatherings (36.9%), access to social venues (35.5%), or sharing the same workspace (21.5%). Younger age, no intent for vaccination, and not believing vaccination to be an important step in surmounting the pandemic were factors associated with certificate non-acceptance. CONCLUSION: This large population-based study showed that the general adult population in Geneva, Switzerland, agreed with the implementation of vaccination certificates in work-related and travel-related contexts. However, this solution was perceived as unnecessary for access to large gatherings or social venues, or to share the same workspace. Differences were seen with age, sex, education, socioeconomic status, and vaccination willingness and perception, highlighting the importance of taking personal and sociodemographic variation into consideration when predicting acceptance of such certificates.

COVID-19 vaccination acceptance in the canton of Geneva: a cross-sectional population-based study.

OBJECTIVE: This study aimed to assess acceptance of COVID-19 vaccination as well as its sociodemographic and clinical determinants, 3 months after the launch of the vaccination programme in Geneva, Switzerland. METHODS: In March 2021, an online questionnaire was proposed to adults included in a longitudinal cohort study of previous SARS-CoV-2 serosurveys carried out in the canton of Geneva, which included former participants of a population-based health survey as well as individuals randomly sampled from population registries, and their household members. Questions were asked about COVID-19 vaccination acceptance, reasons for acceptance or refusal and attitudes to vaccination in general. Data on demographic (age, sex, education, income, professional status, living conditions) and health-related characteristics (having a chronic disease, COVID-19 diagnosis, smoking status) were assessed at inclusion in the cohort (December 2020). The overall vaccination acceptance was standardised according to the age, sex, and education distribution in the Geneva population. RESULTS: Overall, 4067 participants (completion rate of 77.4%) responded to the survey between 17 March and 1 April 2021. The mean age of respondents was 53.3 years and 56.0% were women. At the time of the survey, 17.2% of respondents had already been vaccinated with at least one dose or had made an appointment to get vaccinated, and an additional 58.5% intended or rather intended to get vaccinated. The overall acceptance of COVID-19 vaccination standardised to the age, sex and education distribution of the population of Geneva was 71.8%, with a higher acceptance among men than women, older adults compared with younger adults, high-income individuals compared with those with a low income, and participants living in urban and semi-urban areas compared with rural areas. Acceptance was lower among individuals having completed apprenticeships and secondary education than those with tertiary education. The most common reasons reported by participants intending to get vaccinated were the desire to "get back to normal", to protect themselves, their community and/or society,and their relatives or friends against the risk of infection by SARS-CoV-2, as well as the desire to travel. Less than half (45.6%) of participants having children were willing or rather willing to have their children vaccinated against COVID-19 if it were recommended by public health authorities. CONCLUSION: Although our study found a 71.8% weighted acceptance of COVID-19 vaccination, there were noticeable sociodemographic disparities in vaccination acceptance. These data will be useful for public health measures targeting hesitant populations when developing health communication strategies.

Changes in socioeconomic resources and mental health after the second COVID-19 wave (2020-2021): a longitudinal study in Switzerland.

BACKGROUND: During the 2020/2021 winter, the labour market was under the impact of the COVID-19 pandemic. Changes in socioeconomic resources during this period could have influenced individual mental health. This association may have been mitigated or exacerbated by subjective risk perceptions, such as perceived risk of getting infected with SARS-CoV-2 or perception of the national economic situation. Therefore, we aimed to determine if changes in financial resources and employment situation during and after the second COVID-19 wave were prospectively associated with depression, anxiety and stress, and whether perceptions of the national economic situation and of the risk of getting infected modified this association. METHODS: One thousand seven hundred fifty nine participants from a nation-wide population-based eCohort in Switzerland were followed between November 2020 and September 2021. Financial resources and employment status were assessed twice (Nov2020-Mar2021, May-Jul 2021). Mental health was assessed after the second measurement of financial resources and employment status, using the Depression, Anxiety and Stress Scale (DASS-21). We modelled DASS-21 scores with linear regression, adjusting for demographics, health status, social relationships and changes in workload, and tested interactions with subjective risk perceptions. RESULTS: We observed scores above thresholds for normal levels for 16% (95%CI = 15-18) of participants for depression, 8% (95%CI = 7-10) for anxiety, and 10% (95%CI = 9-12) for stress. Compared to continuously comfortable or sufficient financial resources, continuously precarious or insufficient resources were associated with worse scores for all outcomes. Increased financial resources were associated with higher anxiety. In the working-age group, shifting from full to part-time employment was associated with higher stress and anxiety. Perceiving the Swiss economic situation as worrisome was associated with higher anxiety in participants who lost financial resources or had continuously precarious or insufficient resources. CONCLUSION: This study confirms the association of economic stressors and mental health during the COVID-19 pandemic and highlights the exacerbating role of subjective risk perception on this association.

Seroprevalence trends of anti-SARS-CoV-2 antibodies and associated risk factors: a population-based study.

PURPOSE: We aimed to assess the seroprevalence trends of SARS-CoV-2 antibodies in several Swiss cantons between May 2020 and September 2021 and investigate risk factors for seropositivity and their changes over time. METHODS: We conducted repeated population-based serological studies in different Swiss regions using a common methodology. We defined three study periods: May-October 2020 (period 1, prior to vaccination), November 2020-mid-May 2021 (period 2, first months of the vaccination campaign), and mid-May-September 2021 (period 3, a large share of the population vaccinated). We measured anti-spike IgG. Participants provided information on sociodemographic and socioeconomic characteristics, health status, and adherence to preventive measures. We estimated seroprevalence with a Bayesian logistic regression model and the association between risk factors and seropositivity with Poisson models. RESULTS: We included 13,291 participants aged 20 and older from 11 Swiss cantons. Seroprevalence was 3.7% (95% CI 2.1-4.9) in period 1, 16.2% (95% CI 14.4-17.5) in period 2, and 72.0% (95% CI 70.3-73.8) in period 3, with regional variations. In period 1, younger age (20-64) was the only factor associated with higher seropositivity. In period 3, being aged ≥ 65 years, with a high income, retired, overweight or obese or with other comorbidities, was associated with higher seropositivity. These associations disappeared after adjusting for vaccination status. Seropositivity was lower in participants with lower adherence to preventive measures, due to a lower vaccination uptake. CONCLUSIONS: Seroprevalence sharply increased over time, also thanks to vaccination, with some regional variations. After the vaccination campaign, no differences between subgroups were observed.

Parental willingness to have children vaccinated against COVID-19 in Geneva, Switzerland: a cross-sectional population-based study.

OBJECTIVE: We aimed to examine factors associated with parental willingness to vaccinate their children against COVID-19. METHODS: We surveyed adults included in a digital longitudinal cohort study composed of participants in previous SARS-CoV-2 serosurveys conducted in Geneva, Switzerland. In February 2022, an online questionnaire collected information on COVID-19 vaccination acceptance, parental willingness to vaccinate their children aged ≥5 years and reasons for vaccination preference. We used multivariable logistic regression to assess the demographic, socioeconomic and health-related factors associated with being vaccinated and with parental intention to vaccinate their children. RESULTS: We included 1,383 participants (56.8% women; 69.3% aged 35-49 years). Parental willingness to vaccinate their children increased markedly with the child's age: 84.0%, 60.9% and 21.2%, respectively, for parents of adolescents aged 16-17 years, 12-15 years and 5-12 years. For all child age groups, unvaccinated parents more frequently indicated not intending to vaccinate their children than vaccinated parents. Refusal to vaccine children was associated with having a secondary education (1.73; 1.18-2.47) relative to a tertiary education and with middle (1.75; 1.18-2.60) and low (1.96; 1.20-3.22) household income relative to high income. Refusal to vaccine their children was also associated with only having children aged 12-15 years (3.08; 1.61-5.91), aged 5-11 years (19.77; 10.27-38.05), or in multiple age groups (6.05; 3.22-11.37), relative to only having children aged 16-17 years. CONCLUSION: Willingness to vaccinate children was high for parents of adolescents aged 16-17 years but decreased significantly with decreasing child age. Unvaccinated, socioeconomically disadvantaged parents and those with younger children were less likely to be willing to vaccinate their children. These results are important for vaccination programs and developing communication strategies to reach vaccine-hesitant groups, both in the context of COVID-19 and in the prevention of other diseases and future pandemics.

Seroprevalence of anti-SARS-CoV-2 antibodies and cross-variant neutralization capacity after the Omicron BA.2 wave in Geneva, Switzerland: A population-based study.

Background: More than two years into the COVID-19 pandemic, most of the population has developed anti-SARS-CoV-2 antibodies from infection and/or vaccination. However, public health decision-making is hindered by the lack of up-to-date and precise characterization of the immune landscape in the population. Here, we estimated anti-SARS-CoV-2 antibodies seroprevalence and cross-variant neutralization capacity after Omicron became dominant in Geneva, Switzerland. Methods: We conducted a population-based serosurvey between April 29 and June 9, 2022, recruiting children and adults of all ages from age-stratified random samples of the general population of Geneva, Switzerland. We tested for anti-SARS-CoV-2 antibodies using commercial immunoassays targeting either the spike (S) or nucleocapsid (N) protein, and for antibody neutralization capacity against different SARS-CoV-2 variants using a cell-free Spike trimer-ACE2 binding-based surrogate neutralization assay. We estimated seroprevalence and neutralization capacity using a Bayesian modeling framework accounting for the demographics, vaccination, and infection statuses of the Geneva population. Findings: Among the 2521 individuals included in the analysis, the estimated total antibodies seroprevalence was 93.8% (95% CrI 93.1-94.5), including 72.4% (70.0-74.7) for infection-induced antibodies. Estimates of neutralizing antibodies in a representative subsample (N = 1160) ranged from 79.5% (77.1-81.8) against the Alpha variant to 46.7% (43.0-50.4) against the Omicron BA.4/BA.5 subvariants. Despite having high seroprevalence of infection-induced antibodies (76.7% [69.7-83.0] for ages 0-5 years, 90.5% [86.5-94.1] for ages 6-11 years), children aged <12 years had substantially lower neutralizing activity than older participants, particularly against Omicron subvariants. Overall, vaccination was associated with higher neutralizing activity against pre-Omicron variants. Vaccine booster alongside recent infection was associated with higher neutralizing activity against Omicron subvariants. Interpretation: While most of the Geneva population has developed anti-SARS-CoV-2 antibodies through vaccination and/or infection, less than half has neutralizing activity against the currently circulating Omicron BA.5 subvariant. Hybrid immunity obtained through booster vaccination and infection confers the greatest neutralization capacity, including against Omicron. Funding: General Directorate of Health in Geneva canton, Private Foundation of the Geneva University Hospitals, European Commission ("CoVICIS" grant), and a private foundation advised by CARIGEST SA.

Impact of the COVID-19 pandemic on children and adolescents: determinants and association with quality of life and mental health-a cross-sectional study.

BACKGROUND: The medium-term impact of the COVID-19 pandemic on the wellbeing of children and adolescents remains unclear. More than 2 years into the pandemic, we aimed to quantify the frequency and determinants of having been severely impacted by the COVID-19 pandemic and estimate its impact on health-related quality of life (HRQoL) and mental health. METHODS: Data was drawn from a population-based cohort of children and adolescents, recruited between December 2021 and June 2022, in Geneva, Switzerland. The Coronavirus impact scale was used to assess the multidimensional impact of the pandemic on children through parent's report. A score higher than one standard deviation above the mean was deemed a severe impact. Parents additionally reported about their offspring HRQoL and mental health with validated scales. Determinants of having been severely impacted were assessed with logistic models, as were the associations between having experienced a severe impact and poor HRQoL or mental health. RESULTS: Out of 2101 participants aged 2-17, 12.7% had experienced a severe pandemic impact. Having a lasting health condition, a pandemic-related worsening of lifestyle habits or an unfavorable family environment were associated with having been severely impacted by the pandemic, while a previous anti-SARS-CoV-2 infection was not. Participants who had experienced a severe pandemic impact were more likely to present poor HRQoL (aOR = 3.1; 95% CI 2.3-4.4) and poor mental health (aOR = 3.9; 95% CI 2.5-6.2). CONCLUSION: The COVID-19 pandemic may have persistent consequences on the wellbeing of children and adolescents, especially among those with health and family vulnerabilities.

Prevalence and predictors of psychological distress before, during, and after a COVID-19 pandemic wave in Switzerland, 2021.

There are concerns about acute and long-term mental health effects of the COVID-19 pandemic. This study examined the prevalence and predictors of psychological distress before, during, and after a pandemic wave in Switzerland, 2021. Prevalence of psychological distress was estimated in adults aged 35-96 years using the General Health Questionnaire-12 administered in June 2021 (Specchio-COVID19 cohort, N = 3965), and compared to values from 2003 to 2006 (CoLaus|PsyCoLaus cohort, N = 5667). Anxiety and depression were assessed from February to June 2021 using the Generalised Anxiety Disorder scale-2 and the Patient Health Questionnaire-2, respectively. Prevalence of psychological distress in June 2021, after the pandemic wave (16.0% [95% CI, 14.6%-17.4%]) was comparable to pre-pandemic levels (15.1% [14.0%-16.2%]). Anxiety and depression were highest at the start of the pandemic wave in February 2021, and declined from February to June with the relaxation of measures. Predictors of psychological distress included being younger, female, a single parent, unemployed, a change in working hours or job loss in the past 6 months, greater perceived severity and contagiousness of COVID-19, and self-reported post COVID-19. By June 2021, following a pandemic wave, prevalence of psychological distress in Switzerland was closer to pre-pandemic levels. These findings highlight the need for additional mental health support during times of stricter government policies relating to COVID-19; yet they also suggest that individuals can adapt relatively quickly to the changing context.

Associations between Depression and Self-Reported COVID-19 Symptoms among Adults: Results from Two Population-Based Seroprevalence Studies in Switzerland.

(1) Mental health may modulate the perceived risk of SARS-CoV-2 infection. However, it is unclear how psychological symptoms may distort symptom perception of COVID-19 and SARS-CoV-2 infection. We assessed whether depressive symptoms predicted self-reported COVID-19 symptoms, independently of serologically confirmed SARS-CoV-2 infection. (2) Participants (aged 20-64) in the Geneva (N = 576) and Ticino (N = 581) Swiss regions completed the Patient Health Questionnaire before being tested for anti-SARS-CoV-2 IgG antibodies and recalled COVID-19-compatible symptoms on two occasions: April-July 2020 (baseline), and January-February 2021 (follow-up). We estimated prevalence ratios for COVID-19 symptoms by depression scores in interaction with serological status. (3) At baseline, in Geneva, higher depression predicted higher probability of reporting systemic, upper airways, and gastro-intestinal symptoms, and fever and/or cough; in Ticino, higher depression predicted systemic, upper airways, and gastro-intestinal symptoms, fever and/or cough, dyspnea, and headache. At follow-up, in Geneva, higher depression predicted higher probability of reporting systemic symptoms and dyspnea; in Ticino, higher depression predicted higher probability of reporting systemic and upper airways symptoms, dyspnea and headache (all p values < 0.05). (4) We found positive associations between depressive symptoms and COVID-19-compatible symptoms, independently of seropositivity. Mental wellbeing has relevant public health implications because it modulates self-reported infection symptoms that inform testing, self-medication, and containment measures, including quarantine and isolation.

Persistent symptoms after SARS-CoV-2 infection in children: a cross-sectional population-based serological study.

OBJECTIVES: To estimate the prevalence of children and adolescents reporting persistent symptoms after SARS-CoV-2 infection. DESIGN: A random sample of children and adolescents participated with their family members to a serological survey including a blood drawing for detecting antibodies targeting the SARS-CoV-2 nucleocapsid (N) protein and a questionnaire on COVID-19-related symptoms experienced since the beginning of the pandemic. SETTING: The study took place in the canton of Geneva, Switzerland, between June and July 2021. PARTICIPANT: 660 children aged between 2 and 17 years old. PRIMARY AND SECONDARY OUTCOME: The primary outcome was the persistence of symptoms beyond 4 weeks comparing seropositive and seronegative participants. The type of declared symptoms were also studied as well as associated risk factors. RESULTS: Among seropositive children, the sex-adjusted and age-adjusted prevalence of symptoms lasting longer than 2 weeks was 18.3%, compared with 11.1% among seronegatives (adjusted prevalence difference (ΔaPrev)=7.2%, 95% CI: 1.5% to 13.0%). Among adolescents aged 12-17 years, we estimated the prevalence of experiencing symptoms lasting over 4 weeks to be 4.4% (ΔaPrev,95% CI: -3.8% to 13.6%), whereas no seropositive child aged 2-11 reported symptoms of this duration. The most frequently declared symptoms were fatigue, headache and loss of smell. CONCLUSIONS: We estimated the prevalence of experiencing persistent symptoms lasting over 4 weeks to be around 4% among adolescents, which represents a large absolute number, and should raise awareness and concern. We did not observe meaningful differences of persistent symptoms between seropositive and seronegative younger children, suggesting that they may be less affected than their older counterparts.

A population-based serological study of post-COVID syndrome prevalence and risk factors in children and adolescents.

Post-COVID syndrome remains poorly studied in children and adolescents. Here, we aimed to investigate the prevalence and risk factors of pediatric post-COVID in a population-based sample, stratifying by serological status. Children from the SEROCoV-KIDS cohort study (State of Geneva, Switzerland), aged 6 months to 17 years, were tested for anti-SARS-CoV-2 N antibodies (December 2021-February 2022) and parents filled in a questionnaire on persistent symptoms in their children (lasting over 12 weeks) compatible with post-COVID. Of 1034 children tested, 570 (55.1%) were seropositive. The sex- and age-adjusted prevalence of persistent symptoms among seropositive children was 9.1% (95%CI: 6.7;11.8) and 5.0% (95%CI: 3.0;7.1) among seronegatives, with an adjusted prevalence difference (ΔaPrev) of 4.1% (95%CI: 1.1;7.3). Stratifying per age group, only adolescents displayed a substantial risk of having post-COVID symptoms (ΔaPrev = 8.3%, 95%CI: 3.5;13.5). Identified risk factors for post-COVID syndrome were older age, having a lower socioeconomic status and suffering from chronic health conditions, especially asthma. Our findings show that a significant proportion of seropositive children, particularly adolescents, experienced persistent COVID symptoms. While there is a need for further investigations, growing evidence of pediatric post-COVID urges early screening and primary care management.

Socio-economic determinants of SARS-CoV-2 infection: Results from a population-based cross-sectional serosurvey in Geneva, Switzerland.

Background: SARS-CoV-2 infection and its health consequences have disproportionally affected disadvantaged socio-economic groups globally. This study aimed to analyze the association between socio-economic conditions and having developed antibodies for-SARS-CoV-2 in a population-based sample in the canton of Geneva, Switzerland. Methods: Data was obtained from a population-based serosurvey of adults in Geneva and their household members, between November and December, 2020, toward the end of the second pandemic wave in the canton. Participants were tested for antibodies for-SARS-CoV-2. Socio-economic conditions representing different dimensions were self-reported. Mixed effects logistic regressions were conducted for each predictor to test its association with seropositive status as the main outcome. Results: Two thousand eight hundred and eighty-nine adults completed the study questionnaire and were included in the final analysis. Retired participants and those living in suburban areas had lower odds of a seropositive result when compared to employed participants (OR: 0.42, 95% CI: 0.20-0.87) and those living in urban areas (OR: 0.67, 95% CI: 0.46-0.97), respectively. People facing financial hardship for less than a year had higher odds of a seropositive result compared to those who had never faced them (OR: 2.23, 95% CI: 1.01-4.95). Educational level, occupational position, and household income were not associated with being seropositive, nor were ethnicity or country of birth. Discussion: While conventional measures of socio-economic position did not seem to be related to the risk of being infected in this sample, this study sheds lights on the importance of examining the broader social determinants of health when evaluating the differential impact of the pandemic within the population.

Determinants of adolescents' Health-Related Quality of Life and psychological distress during the COVID-19 pandemic.

BACKGROUND: We examined the determinants of adolescents' Health-Related Quality of Life (HRQoL) and psychological distress (self-reported and parent-reported) during the COVID-19 pandemic, using a random sample of the population of Geneva, Switzerland. METHODS: Data was drawn from participants aged 14-17 years, who participated with their families to a serosurvey conducted in November and December 2020. Adolescents' HRQoL was evaluated using the validated adolescent-reported KIDSCREEN-10 and parent-reported KINDL® scales. Psychological distress was assessed with self-reported sadness and loneliness, and using the KINDL® emotional well-being scale. Using generalized estimating equations, we examined the role of socio-demographic, family and behavioural characteristics in influencing adolescents' mental health status and wellbeing. RESULTS: Among 240 adolescents, 11% had a low HRQoL, 35% reported sadness and 23% reported loneliness. Based on parents' perception, 12% of the adolescents had a low HRQoL and 16% a low emotional well-being. Being a girl (aOR = 3.20; 95%CI: 1.67-6.16), increased time on social media (aOR = 2.07; 95%CI: 1.08-3.97), parents' average to poor mood (aOR = 2.62; 95%CI: 1.10-6.23) and average to poor household financial situation (aOR = 2.31; IC95%: 1.01-6.10) were associated with an increased risk of sadness. Mismatches between adolescents' and their parents' perception of HRQoL were more likely for girls (aOR = 2.88; 95%CI: 1.54-5.41) and in households with lower family well-being (aOR = 0.91; 95%CI: 0.86-0.96). CONCLUSIONS: A meaningful proportion of adolescents experienced low well-being during the second wave of COVID-19, and average well-being was lower than pre-pandemic estimates. Adolescents living in underprivileged or distressed families seemed particularly affected. Monitoring is necessary to evaluate the long-term effects of the pandemic on adolescents.

The Corona Immunitas Digital Follow-Up eCohort to Monitor Impacts of the SARS-CoV-2 Pandemic in Switzerland: Study Protocol and First Results

Objectives: To describe the rationale, organization, and procedures of the Corona Immunitas Digital Follow-Up (CI-DFU) eCohort and to characterize participants at baseline. Methods: Participants of Corona Immunitas, a population-based nationwide SARS-CoV-2 seroprevalence study in Switzerland, were invited to join the CI-DFU eCohort in 11 study centres. Weekly online questonnaires cover health status changes, prevention measures adherence, and social impacts. Monthly questionnaires cover additional prevention adherence, contact tracing apps use, vaccination and vaccine hesitancy, and socio-economic changes. Results: We report data from the 5 centres that enrolled in the CI-DFU between June and October 2020 (covering Basel City/Land, Fribourg, Neuchâtel, Ticino, Zurich). As of February 2021, 4636 participants were enrolled and 85,693 weekly and 27,817 monthly questionnaires were collected. Design-based oversampling led to overrepresentation of individuals aged 65+ years. People with higher education and income were more likely to enroll and be retained. Conclusion: Broad enrolment and robust retention of participants enables scientifically sound monitoring of pandemic impacts, prevention, and vaccination progress. The CI-DFU eCohort demonstrates proof-of-principle for large-scale, federated eCohort study designs based on jointly agreed principles and transparent governance.

Seroprevalence of anti-SARS-CoV-2 IgG antibodies, risk factors for infection and associated symptoms in Geneva, Switzerland: a population-based study.

Aims: To assess SARS-CoV-2 seroprevalence over the first epidemic wave in the canton of Geneva, Switzerland, as well as risk factors for infection and symptoms associated with IgG seropositivity. Methods: Between April and June 2020, former participants of a representative survey of the 20-74-year-old population of canton Geneva were invited to participate in the study, along with household members aged over 5 years. Blood samples were tested for anti-SARS-CoV-2 immunoglobulin G. Questionnaires were self-administered. We estimated seroprevalence with a Bayesian model accounting for test performance and sampling design. Results: We included 8344 participants, with an overall adjusted seroprevalence of 7.8% (95% credible interval 6.8-8.9). Seroprevalence was highest among 18-49 year-olds (9.5%), and lowest in 5-9-year-old children (4.3%) and individuals >65 years (4.7-5.4%). Odds of seropositivity were significantly reduced for female retirees and unemployed men compared to employed individuals, and smokers compared to non-smokers. We found no significant association between occupation, level of education, neighborhood income and the risk of being seropositive. The symptom most strongly associated with seropositivity was anosmia/dysgeusia. Conclusions: Anti-SARS-CoV-2 population seroprevalence remained low after the first wave in Geneva. Socioeconomic factors were not associated with seropositivity in this sample. The elderly, young children and smokers were less frequently seropositive, although it is not clear how biology and behaviours shape these differences.

Forgoing healthcare during the COVID-19 pandemic in Geneva, Switzerland - A cross-sectional population-based study.

BACKGROUND: Health systems around the world continue to navigate through operational challenges surfaced by the coronavirus disease 2019 (COVID-19) pandemic; these have implications for access to healthcare. In this study, we estimate the prevalence and reasons for forgoing healthcare during the pandemic in Geneva, Switzerland; a country with a universal and mandatory private health insurance coverage. METHODS: Participants from a randomly selected population-based sample of the adult population living in the Canton of Geneva completed an online socio-demographic and lifestyle questionnaire between November 2020 and January 2021. The prevalence and reasons for forgoing healthcare since the beginning of the COVID-19 pandemic were examined descriptively, and logistic regression models were used to assess determinants for forgoing healthcare. RESULTS: The study included 5397 participants, among which 8.0% reported having forgone healthcare since the beginning of the COVID-19 pandemic; participants with a disadvantaged financial situation (OR = 2.04; 95% CI: 1.56-2.65), and those reporting an average (OR = 2.54; 95% CI: 1.94-3.31) or poor health (OR = 4.40; 95% CI: 2.39-7.67) were more likely to forgo healthcare. The most common reasons to forgo healthcare were appointment cancellations by healthcare providers (53.9%), fear of infection (35.3%), and personal organizational issues (11.1%). CONCLUSION: Our paper highlights the effects of the COVID-19 pandemic on access to healthcare and identifies population sub-groups at-risk for forgoing healthcare. These results necessitate public health efforts to ensure equitable and accessible healthcare as the COVID-19 pandemic continues.