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Binding antibody levels against SARS-CoV-2 have shown to be correlates of protection against infection with pre-Omicron lineages. This has been challenged by the emergence of immune-evasive variants, notably the Omicron sublineages, in an evolving immune landscape with high levels of cumulative incidence and vaccination coverage. This in turn limits the use of commercially available high-throughput methods to quantify binding antibodies as a tool to monitor protection at the population-level. In this work, we leverage repeated serological measurements between April 2020 and December 2021 on 1083 participants of a population-based cohort in Geneva, Switzerland, to evaluate anti-Spike RBD antibody levels as a correlate of protection against Omicron BA.1/BA.2 infections during the December 2021-March 2022 epidemic wave. We do so by first modeling antibody dynamics in time with kinetic models. We then use these models to predict antibody trajectories into the time period where Omicron BA.1/BA.2 were the predominant circulating sub-lineages and use survival analyses to compare the hazard of having a positive SARS-CoV-2 test by antibody level, vaccination status and infection history. We find that antibody kinetics in our sample are mainly determined by infection and vaccination history, and to a lesser extent by demographics. After controlling for age and previous infections (based on anti-nucleocapsid serology), survival analyses reveal a significant reduction in the hazard of having a documented positive SARS-CoV-2 infection during the Omicron BA.1/BA.2 wave with increasing antibody levels, reaching up to a three-fold reduction for anti-S antibody vels above 800 IU/mL (HR 0.30, 95% CI 0.22-0.41). However, we did not detect a eduction in hazard among uninfected participants. Taken together these results indicate that nti-Spike RBD antibody levels, as quantified by the immunoassay used in this study, are an direct correlate of protection against Omicron BA.1/BA.2 for individuals with a history of revious SARS-CoV-2 infection. Despite the uncertainty in what SARS-COV-2 variant will me next, these results provide reassuring insights into the continued interpretation of ARS-CoV-2 binding antibody measurements as an independent marker of protection at both the individual and population levels.
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BackgroundThe medium-term impact of the COVID-19 pandemic on the wellbeing of children and adolescents remains unclear. More than two 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. MethodsData was drawn from a population-based cohort of children and adolescents, recruited between December 2021 and June 2022, in Geneva, Switzerland. We measured the impact of the pandemic via the Coronavirus impact scale, which assesses the multidimensional impact of the pandemic at the child and family level through parents 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. ResultsOut 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. 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). ConclusionsThe COVID-19 pandemic may have persistent consequences on the wellbeing of children and adolescents, especially among those with health and family vulnerabilities.
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AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSObjectivesC_ST_ABSPost-COVID syndrome remain poorly studied in children and adolescents. In this study, we aimed to investigate the prevalence and risk factors of pediatric post-COVID in a population-based sample, stratifying by serological status. Study designWe used data from the SEROCoV-KIDS cohort study (State of Geneva, Switzerland), which included children (aged 6 months to 17 years) selected from random samples drawn from state registries or who had a household member participating in a COVID-19 seroprevalence study conducted by our group. Children were tested for anti-SARS-CoV-2 N antibodies. Parents filled in a questionnaire on persistent symptoms in their children (lasting over 12 weeks) compatible with post-COVID syndrome. ResultsFrom December 1st, 2021 to February 16th, 2022, 1034 children were included, among whom 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 ({Delta}aPrev) of 4.1% (95%CI: 1.1;7.3). After stratification by age group, the prevalence was higher among adolescents aged 12-17 years ({Delta}aPrev=8.3%, 95%CI: 3.5;13.5) than among younger children (0.0%, 95%CI: -5.2;5.2 among 6-11 years old and 4.2%; 95%CI: -4.4;13.3 among 0-5 years old). The most frequently declared persistent symptoms among seropositives were smell loss, trouble concentrating and abdominal pain. Older age, having a chronic condition and lower socioeconomic conditions were identified as risk factors. ConclusionA significant proportion of seropositive children, particularly adolescents, experienced persistent symptoms. While there is a need for further investigation, growing evidence of pediatric post-COVID syndrome urges early screening and primary care management.
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BackgroundMore than two years into the COVID-19 pandemic, it is generally assumed that 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. We thus aimed to estimate anti-SARS-CoV-2 antibodies seroprevalence and cross-variant neutralization capacity after Omicron became dominant in Geneva, Switzerland. MethodsWe conducted a population-based serosurvey between April 29th and June 9th, 2022, recruiting children and adults of all ages from age-stratified random samples of the Geneva general population. Anti-SARS-CoV-2 antibody presence was assessed using commercial immunoassays targeting either the spike (S) or nucleocapsid (N) protein. Antibodies neutralization capacity against different SARS-CoV-2 variants was evaluated using a cell-free Spike trimer-ACE2 binding-based surrogate neutralization assay. Seroprevalence of anti-SARS-CoV-2 antibodies and neutralization capacity were estimated using Bayesian modeling frameworks accounting for the demographics, vaccination, and infection statuses of the Geneva population. ResultsAmong the 2521 individuals included in the analysis (55.2% women; 21.4% aged <18 years and 14.2% aged [≥] 65 years), overall seroprevalence of antibodies was 93.8% (95% credible interval: 93.1-94.5), including 72.4% (70.0-74.7) for infection-induced antibodies. Estimates of neutralizing antibodies based on a representative subsample of 1160 participants 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. In general, higher levels of neutralization activity against pre-Omicron variants were associated with vaccination, particularly having received a booster dose. Higher levels of neutralization activity against Omicron subvariants were associated with booster vaccination alongside recent infection. ConclusionMore than nine in ten individuals in the Geneva population have developed anti-SARS-CoV-2 antibodies through vaccination and/or infection, but less than half of the population has antibodies with neutralizing activity against the currently circulating Omicron BA.5 subvariant. Hybrid immunity obtained through booster vaccination and infection appears to confer the greatest neutralization capacity, including against Omicron.
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BackgroundSARS-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 anti-SARS-CoV-2 antibodies in a population-based sample in the canton of Geneva, Switzerland. MethodsData was obtained from a population-based serosurvey of adults in Geneva and their household members, between November and December, 2020, towards the end of the second pandemic wave in the canton. Participants were tested for anti-SARS-CoV-2 antibodies. 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. Results2,889 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. DiscussionWhile traditional 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.
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BackgroundThe rapid worldwide spread of the mildly pathogenic SARS-CoV-2 Omicron variant has led to the suggestion that it will induce levels of collective immunity that will help putting an end to the COVID19 pandemics. MethodsConvalescent serums from non-hospitalized individuals previously infected with Alpha, Delta or Omicron BA.1 SARS-CoV-2 or subjected to a full mRNA vaccine regimen were evaluated for their ability to neutralize a broad panel of SARS-CoV-2 variants. FindingsPrior vaccination or infection with the Alpha or to a lesser extent Delta strains conferred robust neutralizing titers against most variants, albeit more weakly against Beta and even more Omicron. In contrast, Omicron convalescent serums only displayed low level of neutralization activity against the cognate virus and were unable to neutralize other SARS-CoV-2 variants. InterpretationModerately symptomatic Omicron infection is only poorly immunogenic and does not represent a substitute for vaccination. FundingEPFL COVID Fund; private foundation advised by CARIGEST SA; Private Foundation of the Geneva University Hospitals; General Directorate of Health of the canton of Geneva, the Swiss Federal Office of Public Health.
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BackgroundVarious studies showed the negative impact of COVID-19-related lockdowns and school closures on the well-being of children and adolescents. However, the prevalence and consequences of occasional short-term school disruptions due to COVID-19-related quarantine or isolation remain unknown. This study evaluated their impact on the well-being and stress level of children and adolescents. MethodsIn June/July 2021, we conducted a survey selecting a representative sample of children and adolescents of a Swiss canton population. Parents of school-aged children reported information about them missing school because of COVID-19, from August 2020 to June 2021, as well as about their health-related quality of life (HRQoL) measured with the KINDL(R) scale and their stress level. ResultsAmong the 538 participants, 216/538 (40.1%) pupils missed school at least once for COVID-19-related causes, with a total of 272 absences. We observed no relationship between the frequency of COVID-19-related absences and the HRQoL or stress level, even when stratifying by the type of absence or socio-demographic factors. DiscussionOverall, these findings are reassuring in that quarantines and related school disruptions, which we know are a common and effective way of controlling SARS-CoV-2 transmission, did not seem to meaningfully impact children and adolescents wellbeing and stress. Finding the right balance between SARS-CoV-2 control and young populations well-being is challenging, and the current results provide additional information for decision makers.
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AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSBackgroundC_ST_ABSIt is now established that a significant proportion of adults experience persistent symptoms after SARS-CoV-2 infection. However, evidence for children and adolescents is still inconclusive. In this population-based study, we examine the proportion of children and adolescents reporting persistent symptoms after SARS-CoV-2 infection, as assessed by serological status, and compare this to a seronegative control group. MethodsWe conducted a serosurvey in June-July 2021, recruiting 660 children and adolescents from 391 households selected randomly from the Geneva population. We tested participants for anti-SARS-CoV-2 antibodies targeting the nucleocapsid (N) protein to determine previous infection. A parent filled a questionnaire including questions on COVID-19-related symptoms lasting at least 2 weeks. FindingsAmong children seropositive for anti-SARS-CoV-2 antibodies, the sex- and age-adjusted prevalence of symptoms lasting longer than two weeks was 18.3%, compared to 11.1% among seronegative children (prevalence difference ({Delta}aPrev)=7.2%, 95%CI:1.5-13.0). Main symptoms declared among seropositive children were fatigue (11.5%) and headache (11.1%). For 8.6% (aPrev, 95%CI: 4.7-12.5) of seropositives, these symptoms were declared to be highly limiting of daily activities. Adolescents aged 12-17 years had a higher adjusted prevalence of persistent symptoms (aPrev=29.1%, 95%CI:19.4-38.7) than younger children. Comparing seropositive and seronegative adolescents, the estimated prevalence of symptoms lasting over four weeks is 4.4% ({Delta}aPrev, 95%CI:-3.8-13.6). InterpretationA significant proportion of children aged 12 to 17 years had symptoms lasting over two weeks after SARS-CoV-2 infection, with an estimated prevalence of symptoms lasting over 4 weeks of 4.4% in this age group. This represents a large number of adolescents in absolute terms, and should raise concern in the context of unknown long-term evolution of symptoms. Younger children appear to experience long-lasting symptoms less frequently, as no difference was observed between the seropositive and seronegative sample. Further studies with larger samples sizes are needed. FundingSwiss Federal Office of Public Health, Geneva General Directorate of Health, HUG Private Foundation, SSPH+, Fondation des Grangettes.
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We report a prospective epidemiological, virological and serological investigation of a SARS-CoV-2 outbreak in a primary school, as part of a longitudinal, prospective, primary school-based surveillance study. It involved repeated testing of pupils and teachers and household members of participants who tested positive, with rapid antigen tests and/or RT-PCR (Day 0-2 and Day 5-7), serologies on dried capillary blood samples (Day 0-2 and Day 30), contact tracing interviews and SARS-CoV-2 whole genome sequencing. This SARS-CoV-2 outbreak caused by the Alpha variant involved 20 children aged 4 to 6 years from 4 classes, 2 teachers and a total of 4 household members. Infection attack rates were between 11.8 and 62.0% among pupils from the 4 classes, 22.2% among teachers and 0% among non-teaching staff. Secondary attack rate among household members was 15.4%. Symptoms were reported by 63% of infected children, 100% of teachers and 50% of household members. All analysed sequences but one showed 100% identity. Serological tests detected 8 seroconversions unidentified by SARS-CoV-2 virological tests. This study confirmed child-to-child and child-to-adult transmission of the infection. Effective measures to limit transmission in schools have the potential to reduce the overall community circulation.
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BackgroundHealth systems around the world continue to navigate through operational challenges surfaced by the 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. MethodsParticipants 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. ResultsThe study included 5,397 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=2.55; 95% CI: 1.94-3.32) or poor health (OR=4.40; 95% CI: 2.40-7.68) 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%). ConclusionOur 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. HighlightsO_LI8% of the Geneva, Switzerland, adults renounced healthcare in the COVID-19 pandemic C_LIO_LIMain forgoing healthcare reasons are appointment cancellation and fear of infection C_LIO_LIUnderprivileged participants with poor health are more likely to forgo healthcare C_LI
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AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSPurposeC_ST_ABSOur objective was to assess adolescents Health-Related Quality of Life (HRQoL) and psychological distress, from their own and their parents perspective, and to examine associated risk factors during the COVID-19 pandemic in Geneva, Switzerland. MethodsA random sample of adolescents, aged 14-17 years, and their families was invited to a serosurvey in November and December 2020. Adolescents HRQoL was evaluated using the validated adolescent-reported KIDSCREEN-10 and parent-reported KINDL(R) scales. Psychological distress was assessed with self-reported sadness and loneliness, and using the KINDL(R) emotional well-being scale. Risk factors for adolescents low HRQoL and psychological distress were identified using generalized estimating equations and both adolescents and their parents perceptions were compared. ResultsAmong 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=3.29; 95%CI: 1.64-6.57), increased time on social media (aOR=2.05; 95%CI: 1.08-3.88), parents average to poor mood (aOR=2.81; 95%CI: 1.21-6.56) and average to poor household financial situation (aOR=2.30; 95%CI: 1.00-5.29) 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). ConclusionA meaningful proportion of adolescents experienced low well-being during the second wave of COVID-19. Adolescents living in underprivileged or distressed families seemed particularly affected. Monitoring is necessary to evaluate the long-term effects of the pandemic on adolescents. Implications and ContributionThis study describes the psychological well-being of a population-based sample of adolescents in Geneva, Switzerland amid the COVID-19 pandemic, and identifies adolescents at risk of distress. This study provides further insight by comparing adolescents well-being as reported by themselves and their parents.
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BackgroundUp-to-date seroprevalence estimates are critical to describe the SARS-CoV-2 immune landscape in the population and guide public health measures. We aimed to estimate the seroprevalence of anti-SARS-CoV-2 antibodies 15 months into the COVID-19 pandemic and six months into the vaccination campaign. MethodsWe conducted a population-based cross-sectional serosurvey between June 1 and July 7, 2021, recruiting participants from age- and sex-stratified random samples of the general population. We tested participants for anti-SARS-CoV-2 antibodies targeting the spike (S) or nucleocapsid (N) proteins (Roche Elecsys immunoassays). We estimated the anti-SARS-CoV-2 antibodies seroprevalence following vaccination and/or infection (anti-S antibodies), or infection only (anti-N antibodies). ResultsWe included 3355 individuals, of which 1814 (54.1%) were women, 697 (20.8%) were aged <18 years and 449 (13.4%) were aged [≥]65 years, 2161 (64.4%) tested positive for anti-S antibodies, and 906 (27.0%) tested positive for anti-N antibodies. The total seroprevalence of anti-SARS-CoV-2 antibodies was 66.1% (95% credible interval, 64.1-68.0). We estimated that 29.9% (28.0-31.9) of the population developed antibodies after infection; the rest having developed antibodies only via vaccination. Seroprevalence estimates were similar across sexes, but differed markedly across age groups, being lowest among children aged 0-5 years (20.8% [15.5-26.7]) and highest among older adults aged [≥]75 years (93.1% [89.6-96.0]). Seroprevalence of antibodies developed via infection and/or vaccination was higher among participants with a higher educational level. ConclusionsMost adults have developed anti-SARS-CoV-2 antibodies, while most teenagers and children remain vulnerable to infection. As the SARS-CoV-2 Delta variant spreads and vaccination rates stagnate, efforts are needed to address vaccine hesitancy, particularly among younger individuals and socioeconomically disadvantaged groups, and to minimize spread among children.
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ObjectivesThis cohort study including essential workers, assessed the{square}risk and incidence of SARS-CoV-2{square}infection during the second surge of COVID-19 according to baseline serostatus and occupational sector. MethodsEssential workers were selected from a seroprevalence survey cohort in Geneva, Switzerland and were linked to a state centralized registry compiling SARS-CoV-2 infections. Primary outcome was the number of virologically-confirmed infections from serological assessment (between May and September 2020) to January 25, 2021, according to baseline antibody status and stratified by three pre-defined occupational groups (occupations requiring sustained physical proximity, involving brief regular contact or others). Secondary outcomes included the incidence of infection. Results10457 essential workers were included (occupations requiring sustained physical proximity accounted for 3057 individuals, those involving regular brief contact, 3645, and 3755 workers were classified under "Other essential occupations"). After a follow-up period of over 27 weeks, 5 (0.6%) seropositive and 830 (8.5%) seronegative individuals had a positive SARS-CoV-2 test, with an incidence rate of 0.2 (95% CI 0.1 to 0.6) and 3.2 (95% CI 2.9 to 3.4) cases per person-week, respectively. Incidences were similar across occupational groups. Seropositive essential workers had a 93% reduction in the hazard (HR of 0.07, 95% CI 0.03 to 0.17) of having a positive test during follow-up with no significant between-occupational group difference. ConclusionsA ten-fold reduction in the hazard of being virologically tested positive was observed among anti-SARS-CoV-2 seropositive essential workers regardless of their sector of occupation, confirming the seroprotective effect of a previous SARS-CoV2 exposure at least six months after infection. Key messagesO_ST_ABSWhat is already known about this subject?C_ST_ABSRisk of SARS-CoV-2 reinfection is low in the general population and among healthcare workers. What are the new findings?A ten-fold reduction of risk of being virologically tested positive reinfection is observed among anti-SARS-CoV-2 seropositive essential workers of different activity sectors, regardless of their occupation-related risk of exposure. How might this impact on policy or clinical practice in the foreseeable future?Vaccination could be delayed in individuals with previous history of SARS-CoV-2 infection with serologic confirmation, regardless of their occupational exposure. These observations need to be confirmed for new SARS-CoV-2 variants.
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Serosurveys are an important tool to estimate the true extent of the current SARS-CoV-2 pandemic. So far, most serosurvey data have been analysed with cut-off based methods, which dichotomize individual measurements into sero-positives or negatives based on a predefined cutoff. However, mixture model methods can gain additional information from the same serosurvey data. Such methods refrain from dichotomizing individual values and instead use the full distribution of the serological measurements from pre-pandemic and COVID-19 controls to estimate the cumulative incidence. This study presents an application of mixture model methods to SARS-CoV-2 serosurvey data from the SEROCoV-POP study from April and May 2020 in Geneva (2766 individuals). Besides estimating the total cumulative incidence in these data (8.1% (95% CI: 6.8% - 9.8%)), we applied extended mixture model methods to estimate an indirect indicator of disease severity, which is the fraction of cases with a distribution of antibody levels similar to hospitalised COVID-19 patients. This fraction is 51.2% (95% CI: 15.2% - 79.5%) across the full serosurvey, but differs between three age classes: 21.4% (95% CI: 0% - 59.6%) for individuals between 5 and 40 years old, 60.2% (95% CI: 21.5% - 100%) for individuals between 41 and 65 years old and 100% (95% CI: 20.1% - 100%) for individuals between 66 and 90 years old. Additionally, we find a mismatch between the inferred negative distribution of the serosurvey and the validation data of pre-pandemic controls. Overall, this study illustrates that mixture model methods can provide additional insights from serosurvey data.
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BackgroundThe COVID-19 pandemic has affected billions of people around the world both directly through the infection itself and indirectly through its economic, social and sanitary impact. Collecting data over time is essential for the understanding of the disease spread, the incidence of COVID19-like symptoms, the level and dynamics of immunity, as well as the long-term impact of the pandemic. ObjectiveThe objective of the study was to set up a longitudinal follow-up of adult participants of serosurveys carried out in the Canton of Geneva, Switzerland, during the COVID-19 pandemic. MethodsSerosurvey participants were invited to create an account on the dedicated digital platform Specchio-COVID19 (https://www.specchio-covid19.ch/). Upon registration, an initial questionnaire assessed socio-demographic and lifestyle characteristics (including housing conditions, physical activity, diet, alcohol and tobacco consumption), anthropometry, general health, and experience related to COVID-19 (symptoms, COVID-19 test results, quarantines, hospitalizations). Weekly, participants were invited to fill in a short questionnaire with updates on self-reported COVID-19-compatible symptoms, SARS-CoV-2 infection testing and vaccination. A more detailed questionnaire about mental health, well-being, risk perception, and changes in working conditions was proposed monthly. Supplementary questionnaires were proposed at regular intervals to assess more in depth the impact of the pandemic on physical and mental health, vaccination adherence, health care consumption and changes in health behaviors. At baseline, serology testing allowed to assess the spread of SARS-CoV-2 infection among the general population and subgroups of workers. Additionally, seropositive participants and a sample of randomly selected participants were invited for serologic testing at regular intervals in order to monitor both the seropersistance of anti-SARS-CoV-2 antibodies and the seroprevalence of anti-SARS-CoV-2 antibodies in the population of the Canton of Geneva. Ethics and disseminationThe study was approved by the Cantonal Research Ethics Commission of Geneva, Switzerland (CCER Project ID 2020-00881). Results will be disseminated in a variety of ways, via the Specchio-COVID19 platform, social media posts, press releases, and through regular scientific dissemination methods (open-access articles, conferences). Article summaryO_ST_ABSStrengths and limitationsC_ST_ABSO_LIThis is a large study with a diversified recruitment among the general population and mobilized workers. It will contribute to obtain a clearer picture of the impact of the COVID-19 pandemic, for both the general population and targeted subpopulations. C_LIO_LIA major strength of the study is the combined use of serological testing and questionnaires. While regular serological testing will help us to model evolution of the pandemic, self-reported data on socioeconomic characteristics, COVID-19-compatible symptoms, and general and mental health will allow us to monitor the progression of the COVID-19 pandemic as well as to thoroughly analyze its effects on several dimensions of health. C_LIO_LIThe longitudinal component of the study will provide insight into the extent and duration of immunity, as well as the long-term impact of the pandemic and the sanitary, social and economic measures associated with it. C_LIO_LIThe main limitation is that Specchio-COVID19 is based on self-reports with a risk of information bias. However, considering the pandemic context, participants are generally engaged to participate and to contribute to COVID-19 research. Further, at least half of the sample is based on random selection in the general population. C_LIO_LIThe study is primarily being conducted online, which may limit the generalizability of the findings, especially for the elderly and vulnerable populations, although internet access is extensive in Switzerland. Nonetheless, participants can use paper questionnaires to contribute to the major assessments. C_LI
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ObjectiveThis study aimed to assess acceptance of COVID-19 vaccination as well as its sociodemographic and clinical determinants in a general population sample three months after the launch of the vaccination program in Switzerland. MethodsIn March 2021, an online questionnaire on vaccination acceptance was proposed to adults included in a longitudinal cohort study of previous population-based serosurveys carried out in the canton of Geneva. Questions were asked about COVID-19 vaccination acceptance, reasons of acceptance or refusal, and attitudes about 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). ResultsOverall, 4067 participants (completion rate of 77.4%) responded to the survey between March 17 and April 1, 2021. The mean age of respondents was 53.3 years and 56.0% were women. Most had completed tertiary education (64.7%) and over 60% were currently professionally active. 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 was 75.7%, with a higher acceptance among men compared to women, older adults compared to younger adults, high-income individuals compared to those with a low income, participants living in urban and semi-urban areas compared to rural, and retirees and students compared to employed individuals. Acceptance was lower among individuals having completed apprenticeships and secondary education compared to 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. ConclusionAlthough our study found a 75.7% acceptance of COVID-19 vaccination, there were noticeable socio-demographic disparities in vaccination acceptance. These data will be useful for public health measures targeting hesitant populations when developing health communication strategies. These results will be updated over time with a new release of the survey in autumn 2021.
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PurposeThe Actionable Register of Geneva Out- and inpatients with SARS-CoV-2 (ARGOS) is an ongoing prospective cohort created by the Geneva Directorate of Health (GDH). It consists of an operational database compiling all SARS-CoV-2 test results conducted in the Geneva area since late February 2020. This article aims at presenting this comprehensive cohort, in light of some of the varying public health measures in Geneva, Switzerland, since March 2020. ParticipantsAs of June 1st, 2021, the database included 356868 patients, among which 65475 had at least one positive test result for SARS-CoV-2. Among all positive patients, 37.6% were contacted only once, 10.6 % had one follow-up call, 8.5% had two, and 27.7% had 3 or more follow-up calls. Participation rate among positive patients is 94%. Data collection is ongoing. Findings to dateARGOS data illustrates the magnitude of COVID-19 pandemic in Geneva, Switzerland, and details a variety of population factors and outcomes. The content of the cohort includes demographic data, comorbidities and risk factors for poor clinical outcome, self-reported COVID-19 symptoms, environmental and socio-economic factors, prospective and retrospective contact tracing data, travel quarantine data, and deaths. The registry has already been used in several publications focusing on symptoms and long COVID, infection fatality rate, and re-infection. Future plansThe data of this large real-world registry provides a valuable resource for various types of research, such as clinical research, epidemiological research or policy assessment as it illustrates the impact of public health policies and overall disease burden of COVID-19. STRENGTHS AND LIMITATIONS OF THIS STUDYO_LIARGOS main strength consists of its large number of cases, representative of all diagnosed cases on a regional level with the primary aim of assessing all cases. C_LIO_LIARGOS involves every individual who performed a SARS-CoV-2 test (PCR or antigenic) and is not limited to hospitalized patients, thus providing a valuable resource to assess the overall disease burden of COVID-19 in a geographically defined population. C_LIO_LITo mitigate confounding effects and improve data analysis and interpretation, we present the data according to four policy periods. C_LIO_LIThis cohort is multicentric as it includes all tests performed in Genevas hospitals (both public and private), private practices and medical centers. C_LIO_LIDue to operational needs, symptoms and comorbidities are self-reported, which may lead to measurement error or misclassification. C_LI
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ImportanceSerological assays detecting specific IgG antibodies generated against the Spike protein following Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection are being widely deployed in research studies and clinical practice. However, the duration and the effectiveness of the protection conferred by the immune response against future infection remains to be assessed in a large population. ObjectiveTo estimate the incidence of newly acquired SARS-CoV-2 infections in seropositive individuals from a population-based sample as compared to seronegative controls. DesignRetrospective longitudinal propensity-score matched cohort study. SettingA seroprevalence survey including a population-based representative sample of the population from the canton of Geneva (Switzerland) was conducted between April and June 2020, immediately after the first pandemic wave. Each individual included in the seroprevalence survey was linked to a state centralized registry compiling virologically confirmed SARS-CoV-2 infections since the beginning of the pandemic. ParticipantsParticipants aged twelve years old and over, who developed anti-spike IgG antibodies were matched one-to-two to seronegative controls, using a propensity-score including age, gender, immunodeficiency, body mass index, smoking status and education level. ExposureSARS-CoV-2 seropositivity. Main outcomes and measuresOur primary outcome was virologically confirmed SARS-CoV-2 infections which occurred from serological status assessment in April-June 2020 to the end of the second pandemic wave (January 2021). Additionally, incidence of infections, rate of testing and proportion of positive tests were analysed. ResultsAmong 8344 serosurvey participants, 498 seropositive individuals were selected and matched with 996 seronegative controls. After a mean follow-up of 35.6 (Standard Deviation, SD: 3.2) weeks, 7 out of 498 (1.4%) seropositive subjects had a positive SARS-CoV-2 test, of which 5 (1.0%) were considered as reinfections. By contrast, infection rate was significantly higher in seronegative individuals (15.5%, 154/996) during a similar mean follow-up of 34.7 (SD 3.2) weeks, corresponding to a 94% (95%CI 86% to 98%, P<0.001) reduction in the hazard of having a positive SARS-CoV-2 test for seropositive subjects. Conclusions and relevanceSeroconversion after SARS-CoV-2 infection confers protection to successive viral contamination lasting at least 8 months. These findings could help global health authorities establishing priority for vaccine allocation. Key points QuestionDo SARS-CoV-2 antibodies confer protection against future infection? FindingsIn this retrospective matched cohort study nested in a representative sample of the general population of Geneva, Switzerland, we observed a 94% reduction in the hazard of being infected among participants with antibodies against SARS-CoV-2, when compared to seronegative controls, >8 months after initial serology assessment. MeaningSeroconversion to SARS-CoV-2 is associated with a large and sustained protection against reinfection.
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Serologic studies have been critical in tracking the evolution of the COVID-19 pandemic. The reliability of serologic studies for quantifying the proportion of the population that have been infected depends on the extent of antibody decay as well as on assay performance in detecting both recent and older infections. Data on anti-SARS-CoV-2 antibodies persistence remain sparse, especially from infected individuals with few to no symptoms. In a cohort of mostly mild/asymptomatic SARS-CoV-2-infected individuals tested with three widely-used immunoassays, antibodies persisted for at least 8 months after infection, although detection depended on immunoassay choice, with one of them missing up to 40% of past infections. Simulations reveal that without appropriate adjustment for time-varying assay sensitivity, seroprevalence surveys may underestimate infection rates. As the immune landscape becomes more complex with naturally-infected and vaccinated individuals, assay choice and appropriate assay-performance-adjustment will become even more important for the interpretation of serologic studies.
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To understand the geographical and temporal spread of SARS-CoV-2 during the first wave of infection documented in the canton of Vaud, Switzerland, we analysed clusters of positive cases using the precise place of residence of 33651 individuals tested (RT-PCR) between January 10 and June 30, 2020. We identified both space-time (SaTScan) and transmission (MST-DBSCAN) clusters; we estimated their duration, their transmission behavior (emergence, growth, reduction, etc.) and relative risk. For each cluster, we computed the within number of individuals, their median age and viral load. Among 1684 space-time clusters identified, 457 (27.1%) were significant (p [≤] 0.05), i.e. harboring a higher relative risk of infection, as compared to other regions. They lasted a median of 11 days (IQR 7-13) and included a median of 12 individuals per cluster (IQR 5-20). The majority of significant clusters (n=260; 56.9 %) had at least one person with an extremely high viral load (above 1 billion copies/ml). Those clusters were considerably larger (median of 17 infected individuals, p < 0.001) than clusters with subjects showing a viral load lower than 1 million copies/ml (median of 3 infected individuals). The highest viral loads were found in clusters with the lowest average age, while clusters with the highest average age had low to middle viral load. Interestingly, in 20 significant clusters the viral load of three first cases were all below 100000 copies/ml suggesting that subjects with less than 100000 copies/ml may still have been contagious. Noteworthy, the dynamics of transmission clusters made it possible to identify three diffusion zones, which mainly differentiated rural from urban areas, the latter being more prone to last and spread in a new nearby clusters. The use of geographic information is key for public health decision makers to mitigate the spread of the virus. This study suggests that early localization of clusters help implementing targeted protective measures limiting the spread of the SARS-CoV-2 virus.
