Risk Factors for Community and Intrahousehold Transmission of SARS-CoV-2: Modeling in a Nationwide French Population-Based Cohort Study, the EpiCoV Study.

We assessed the risk of acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from household and community exposure according to age, family ties, and socioeconomic and living conditions using serological data from a nationwide French population-based cohort study, the Epidémiologie et Conditions de Vie (EpiCoV) Study. A history of SARS-CoV-2 infection was defined by a positive anti-SARS-CoV-2 enzyme-linked immunosorbent assay immunoglobulin G result in November-December 2020. We applied stochastic chain binomial models fitted to the final distribution of household infections to data from 17,983 individuals aged ≥6 years from 8,165 households. Models estimated the competing risks of being infected from community and household exposure. The age group 18-24 years had the highest risk of extrahousehold infection (8.9%, 95% credible interval (CrI): 7.5, 10.4), whereas the oldest (≥75 years) and youngest (6-10 years) age groups had the lowest risk, at 2.6% (95% CrI: 1.8, 3.5) and 3.4% (95% CrI: 1.9, 5.2), respectively. Extrahousehold infection was also associated with socioeconomic conditions. Within households, the probability of person-to-person transmission increased with age, from 10.6% (95% CrI: 5.0, 17.9) among children aged 6-10 years to 43.1% (95% CrI: 32.6, 53.2) among adults aged 65-74 years. Transmission was higher between partners (29.9%, 95% CrI: 25.6, 34.3) and from mother to child (29.1%, 95% CrI: 21.4, 37.3) than between individuals related by other family ties. In 2020 in France, the main factors identified for extrahousehold SARS-CoV-2 infection were age and socioeconomic conditions. Intrahousehold infection mainly depended on age and family ties.

Temporal changes in the risk of six-month post-covid symptoms: a national population-based cohort study.

It is unclear how the risk of post-covid symptoms evolved during the pandemic, especially before the spread of Severe Acute Respiratory Syndrome Coronavirus 2 variants and the availability of vaccines. We used modified Poisson regressions to compare the risk of six-month post-covid symptoms and their associated risk factors according to the period of first acute covid: during the French first (March-May 2020) or second (September-November 2020) wave. Non-response weights and multiple imputation were used to handle missing data. Among participants aged 15 or more in a national population-based cohort, the risk of post-covid symptoms was 14.6% (95% CI: 13.9%, 15.3%) in March-May 2020, versus 7.0% (95% CI: 6.3%, 7.7%) in September-November 2020 (adjusted RR: 1.36, 95% CI: 1.20, 1.55). For both periods, the risk was higher in the presence of baseline physical condition(s), and it increased with the number of acute symptoms. During the first wave, the risk was also higher for women, in the presence of baseline mental condition(s), and it varied with educational level. In France in 2020, the risk of six-month post-covid symptoms was higher during the first than the second wave. This difference was observed before the spread of variants and the availability of vaccines.

Anal and oropharyngeal HPV distribution in HIV-negative multipartner MSM using self-sampling kits for HIV and sexually transmitted infection screening.

Men who have sex with men (MSM) are at high risk of sexually transmitted infections, among which HPV infections are particularly prominent. We took advantage of the MémoDépistages study to evaluate HPV distribution at anal and oropharyngeal sites in HIV-negative multipartner MSM. HPV DNA was detected in 82% (n = 344) of anal and 11% (n = 45) of oropharyngeal self-collected samples taken from 421 participants. Multiple HPV types were detected in 70% of anal samples, and single HPV types in 91% of oropharyngeal samples. HPV16 was the most frequent type detected in the anus, followed by HPV6, HPV51, and HPV52. HPV6, HPV16, and HPV11 were the most prevalent types in the oropharynx. HPV targeted by the nonavalent vaccine was detected in 71% and 50% of HPV-positive anal and oropharyngeal samples, respectively. The main risk factor associated with HPV detection was frequenting gay meeting places, living in large cities, and having an anal Chlamydia trachomatis/Neisseria gonorrhoeae infection. In this cohort of highly sexually active MSM, HPV detection was highly frequent and rendered them at high risk of precancerous and cancerous lesions. Universal vaccination against HPV before sexual debut is an important public health strategy to prevent HPV-associated cancers in this highly vulnerable population of HIV-negative MSM.

Dispositifs de dépistage des infections sexuellement transmissibles à domicile : quelle prise en compte des populations LGBT ?

INTRODUCTION: Every days, more than one million people are infected with a sexually transmitted infection worlwide. In France, screening mainly rely on medical laboratories, private or public, with e prescription. Those tests face structural ans social barriers for LGBT people that could be partially lifted using at home self sampling. Using a narrative review, we will study how the needs of those populations are adressed in existing at home self sampling interventions. PURPOSE OF RESEARCH: Describe the adaptation of home sampling system to MSM, WSW and transgender peoples. RESULTS: Nine interventions met our inclusion criteria, eight in English spoken countries. Studies did not systematically reported data on sexual orientation. Transgender people, when identified, were rarely a larger group enough to be the subject of sub-analysis. Infections tested were CT and NG for three intervention, HIV only for one, CT,NG and HIV for five, and one also add HCV. CONCLUSIONS: Standing as a complement to physical testing services, at home self-sampling intervention could benefit from an advertisement to WSW and from the integration of wider sexual health services.

Age, COVID-19-like symptoms and SARS-CoV-2 seropositivity profiles after the first wave of the pandemic in France.

BACKGROUND: The interplay between age and symptoms intensity on antibody response to SARS-CoV-2 infection has not been studied in a general population setting. METHODS: We explored the serologic profile of anti-SARS-CoV-2 antibodies after the first wave of the pandemic, by assessing IgG against the spike protein (ELISA-S), IgG against the nucleocapsid protein (ELISA-NP) and neutralizing antibodies (SN) in 82,126 adults from a French population-based multi-cohort study. RESULTS: ELISA-S positivity was increased in 30- to 49-year-old adults (8.5%) compared to other age groups (5.6% in 20- to 29-year-olds, 2.8% in ≥ 50-year-olds). In the 3681 ELISA-S positive participants, ELISA-NP and SN positivity exhibited a U-shaped relationship with age, with a lower rate in 30- to 49-year-old adults, and was strongly associated with COVID-19-like symptoms. CONCLUSION: Our study confirms the independent role of age and symptoms on the serologic profile of anti-SARS-CoV-2 antibodies, but the non-linear relationship with age deserves further investigation.

Prevalence of SARS-Cov-2 antibodies and living conditions: the French national random population-based EPICOV cohort.

BACKGROUND: We aimed to estimate the seroprevalence of SARS-CoV-2 infection in France and to identify the populations most exposed during the first epidemic wave. METHODS: Random selection of individuals aged 15 years or over, from the national tax register (96% coverage). Socio-economic data, migration history, and living conditions were collected via self-computer-assisted-web or computer-assisted-telephone interviews. Home self-sampling was performed for a random subsample, to detect IgG antibodies against spike protein (Euroimmun), and neutralizing antibodies with in-house assays, in dried blood spots (DBS). RESULTS: The questionnaire was completed by 134,391 participants from May 2nd to June 2st, 2020, including 17,441 eligible for DBS 12,114 of whom were tested. ELISA-S seroprevalence was 4.5% [95% CI 3.9-5.0] overall, reaching up to 10% in the two most affected areas. High-density residences, larger household size, having reported a suspected COVID-19 case in the household, working in healthcare, being of intermediate age and non-daily tobacco smoking were independently associated with seropositivity, whereas living with children or adolescents did not remain associated after adjustment for household size. Adjustment for both residential density and household size accounted for much of the higher seroprevalence in immigrants born outside Europe, twice that in French natives in univariate analysis. CONCLUSION: The EPICOV cohort is one of the largest national representative population-based seroprevalence surveys for COVID-19. It shows the major role of contextual living conditions in the initial spread of COVID-19 in France, during which the availability of masks and virological tests was limited.

Online self-sampling kits to screen multipartner MSM for HIV and other STIs: participant characteristics and factors associated with kit use in the first 3 months of the MemoDepistages programme, France, 2018.

OBJECTIVES: In 2017, to reduce the proportion of men who have sex with men (MSM) in the undiagnosed HIV population in France (38%), HIV screening is advised each 3 months and STI screening is advised each year in multipartner MSM. Despite the range of testing solutions, over 40% of MSM were not tested for HIV and over 50% for STIs in the past year. Based on international experiments that offer screening solutions via online advertising, the French National Health Agency launched a programme (MemoDepistages) to provide a free self-sampling kit (SSK) for HIV and STIs. This article analyses the sociodemographic and behavioural characteristics of MSM in terms of kit acceptance and sample return. METHODS: Participants were registered for the programme online after ordering an SSK. The study included men aged over 18 years, living in one of the four selected French regions, and willing to disclose their postal and email address; they had health insurance, acknowledged more than one male partner in the past year, indicated a seronegative or unknown HIV status and were not taking medically prescribed pre-exposure prophylaxis drugs. Samples were collected by users and posted directly to the laboratory. Characteristics associated with kit acceptance and sample return were analysed using logistic regression. RESULTS: Overall, 7158 eligible MSM were offered to participate in the programme, with 3428 ordering the kit (47.9%) and 1948 returning their sample, leading to a return rate of 56.8% and an overall participation rate of 27.2%. Acceptance and return rates were strongly associated with sociodemographic characteristics, mainly education level but not with behavioural characteristics. Non-college graduates had lower acceptance (44.2%) and return rates (47.7%). CONCLUSION: The programme rapidly recruited a large number of MSM. It removed geographical inequalities related to screening access.

Incidence and risk factors of COVID-19-like symptoms in the French general population during the lockdown period: a multi-cohort study.

BACKGROUND: Our main objectives were to estimate the incidence of illnesses presumably caused by SARS-CoV-2 infection during the lockdown period and to identify the associated risk factors. METHODS: Participants from 3 adult cohorts in the general population in France were invited to participate in a survey on COVID-19. The main outcome was COVID-19-Like Symptoms (CLS), defined as a sudden onset of cough, fever, dyspnea, ageusia and/or anosmia, that lasted more than 3 days and occurred during the 17 days before the survey. We used delayed-entry Cox models to identify associated factors. RESULTS: Between April 2, 2020 and May 12, 2020, 279,478 participants were invited, 116,903 validated the questionnaire and 106,848 were included in the analysis. Three thousand thirty-five cases of CLS were reported during 62,099 person-months of follow-up. The cumulative incidences of CLS were 6.2% (95% Confidence Interval (95%CI): 5.7%; 6.6%) on day 15 and 8.8% (95%CI 8.3%; 9.2%) on day 45 of lockdown. The risk of CLS was lower in older age groups and higher in French regions with a high prevalence of SARS-CoV-2 infection, in participants living in cities > 100,000 inhabitants (vs rural areas), when at least one child or adolescent was living in the same household, in overweight or obese people, and in people with chronic respiratory diseases, anxiety or depression or chronic diseases other than diabetes, cancer, hypertension or cardiovascular diseases. CONCLUSION: The incidence of CLS in the general population remained high during the first 2 weeks of lockdown, and decreased significantly thereafter. Modifiable and non-modifiable risk factors were identified.

HCV and HBV prevalence based on home blood self-sampling and screening history in the general population in 2016: contribution to the new French screening strategy.

BACKGROUND: The advent of effective direct-acting antivirals (DAAs), has prompted an assessment of the French Hepatitis C virus (HCV) screening strategy, which historically targeted high-risk groups. One of the options put forward is the implementation of combined (i.e., simultaneous) HCV, Hepatitis B virus (HBV) and HIV screening for all adults at least once during their lifetime ("universal combined screening"). However, recent national survey-based data are lacking to guide decision-making regarding which new strategy to implement. Accordingly, we aimed to provide updated data for both chronic hepatitis C (CHC) and B (CHB) prevalence and for HCV and HBV screening history, using data from the BaroTest and 2016 Health Barometer (2016-HB) studies, respectively. METHODS: 2016-HB was a national cross-sectional phone based health survey conducted in 2016 among 20,032 randomly selected individuals from the general population in mainland France. BaroTest was a virological sub-study nested in 2016-HB. Data collected for BaroTest were based on home blood self-sampling on dried blood spots (DBS). RESULTS: From 6945 analyzed DBS, chronic hepatitis C (CHC) and B (CHB) prevalence was estimated at 0.30% (95% Confidence Interval (CI): 0.13-0.70) and 0.30% (95% CI: 0.13-0.70), respectively. The proportion of individuals aware of their status was estimated at 80.6% (95% CI: 44.2-95.6) for CHC and 17.5% (95% CI: 4.9-46.4) for CHB. Universal combined screening would involve testing between 32.6 and 85.3% of 15-75 year olds according to whether we consider only individuals not previously tested for any of the three viruses, or also those already tested for one or two of the viruses. CONCLUSIONS: Our data are essential to guide decision-making regarding which new HCV screening recommendation to implement in France. They also highlight that efforts are still needed to achieve the WHO's targets for eliminating these diseases. Home blood self-sampling may prove to be a useful tool for screening and epidemiological studies.

Chlamyweb Study I: rationale, design and acceptability of an internet-based chlamydia testing intervention.

OBJECTIVES: In recent years, the internet has widely facilitated Chlamydia trachomatis home-sampling. In France (2012), the Chlamyweb Study evaluated an intervention (Chlamyweb) involving home-based self-sampling via the internet. One element of the study consisted of a randomised controlled trial (RCT), which is reported in detail elsewhere. The focus of this paper, however, is on describing the Chlamyweb Intervention and reporting on the non-RCT element of the evaluation of that intervention by the Chlamyweb Study. This involves (1) describing the design and roll-out of the Chlamyweb Intervention, (2) comparing the socio-behavioural profiles of the participants in the intervention with a nationally representative general population sample and (3) examining the factors that influence the acceptance and return of a self-sampling kit supplied to participants in the course of the intervention. METHODS: Self-sampling kits were offered to sexually active people aged 18-24 years living on the mainland French. Participants' characteristics were compared with the general population to describe recruited and participant populations. Multivariate analyses by conditional logistic regression were performed to determine factors that were predictors of kit acceptation and use. RESULTS: 7215 people aged 18-24 years were included. Compared with the general population, Chlamyweb reached larger proportions of women, younger people and people with several partners in the previous year. 3372 (46.7%) agreed to receive a self-sampling kit and 2084 (61.8%) returned it, with more women doing so than men. The participation rate was associated with age, place of birth, occupational status, number of partners and condom use, differently for men and women. CONCLUSION: The offer of easy-to-use, self-sampling kits free of charge appeared to be a logistically feasible strategy for testing in France and reached a large and diverse population including individuals who have limited access to the traditional healthcare system. TRIAL REGISTRATION NUMBER: AFFSAPS n° IDRCB 0211-A01000-41; pre-results.

Chlamyweb Study II: a randomised controlled trial (RCT) of an online offer of home-based Chlamydia trachomatis sampling in France.

BACKGROUND: The number of cases of Chlamydia trachomatis (Ct) diagnosed has increased in the past 15 years in France as well as in other European countries. This paper reports a randomised controlled trial (RCT) to evaluate whether the offer of home-based testing over the internet increased the number of young people tested for chlamydia compared with the current testing strategy and to estimate the number and risks factors of the infected population. This RCT took place as an element of the Chlamyweb Study-a study aiming to evaluate an intervention (the Chlamyweb Intervention) involving the offer of a free self-sampling kit online to sexually active men and women aged 18-24 years in France. METHODS: Participants in the Chlamyweb RCT (n=11 075) received either an offer of a free self-sampling kit (intervention group) or were invited to be screened in primary care settings (control group). Risks ratios were used to compare screening rates between the intervention and control groups. Risk factors were analysed for infected people in the intervention group. RESULTS: The screening frequency was about three times higher among young people who received a self-sampling kit than those who only received a tailored recommendation to be screened (29.2% vs 8.7%). Although rates of screening among men were lower than among women (23.9% vs 33.9%), the intervention effect was greater among men (adjusted risk ratios (aRR)=4.55 vs aRR=2.94). Ct positivity (6.8%) was similar to that observed in STI clinics. It was higher in women (8.3%) than in men (4.4%). CONCLUSIONS: These results invite us to consider the establishment of a large home-based screening programme, although additional studies including economic assessments are needed to evaluate the most appropriate combination of strategies in the French context. TRIAL REGISTRAION NUMBER: AFFSAPS n° IDRCB 0211-A01000-41; Results.

Contraceptive Use Measured in a National Population-Based Approach: Cross-Sectional Study of Administrative Versus Survey Data.

BACKGROUND: Prescribed contraception is used worldwide by over 400 million women of reproductive age. Monitoring contraceptive use is a major public health issue that usually relies on population-based surveys. However, these surveys are conducted on average every 6 years and do not allow close follow-up of contraceptive use. Moreover, their sample size is often too limited for the study of specific population subgroups such as people with low income. Health administrative data could be an innovative and less costly source to study contraceptive use. OBJECTIVE: We aimed to explore the potential of health administrative data to study prescribed contraceptive use and compare these data with observations based on survey data. METHODS: We selected all women aged 15-49 years, covered by French health insurance and living in France, in the health administrative database, which covers 98% of the resident population (n=14,788,124), and in the last French population-based representative survey, the Health Barometer Survey, conducted in 2016 (n=4285). In health administrative data, contraceptive use was recorded with detailed information on the product delivered, whereas in the survey, it was self-declared by the women. In both sources, the prevalence of contraceptive use was estimated globally for all prescribed contraceptives and by type of contraceptive: oral contraceptives, intrauterine devices (IUDs), and implants. Prevalences were analyzed by age. RESULTS: There were more low-income women in health administrative data than in the population-based survey (1,576,066/14,770,256, 11% vs 188/4285, 7%, respectively; P<.001). In health administrative data, 47.6% (7034,710/14,770,256; 95% CI 47.6%-47.7%) of women aged 15-49 years used a prescribed contraceptive versus 50.5% (2297/4285; 95% CI 49.1%-52.0%) in the population-based survey. Considering prevalences by the type of contraceptive in health administrative data versus survey data, they were 26.9% (95% CI 26.9%-26.9%) versus 27.7% (95% CI 26.4%-29.0%) for oral contraceptives, 17.7% (95% CI 17.7%-17.8%) versus 19.6% (95% CI 18.5%-20.8%) for IUDs, and 3% (95% CI 3.0%-3.0%) versus 3.2% (95% CI 2.7%-3.7%) for implants. In both sources, the same overall tendency in prevalence was observed for these 3 contraceptives. Implants remained little used at all ages, oral contraceptives were highly used among young women, whereas IUD use was low among young women. CONCLUSIONS: Compared with survey data, health administrative data exhibited the same overall tendencies for oral contraceptives, IUDs, and implants. One of the main strengths of health administrative data is the high quality of information on contraceptive use and the large number of observations, allowing studies of subgroups of population. Health administrative data therefore appear as a promising new source to monitor contraception in a population-based approach. They could open new perspectives for research and be a valuable new asset to guide public policies on reproductive and sexual health.

[Evidence-based and promising interventions to prevent sexually transmitted diseases: a literature review]. / Interventions validées ou prometteuses en prévention des Infections Sexuellement Transmissibles (IST)?: synthèse de la littérature.

There has been a significant increase in the prevalence of sexually transmitted diseases in France over the past decade. The prevention and control of STDs are a major focus of the 2010-2014 national strategic plan on HIV and STDs. This paper reviews the current knowledge of evidence-based programs aimed at preventing sexually transmitted diseases (STDs). The study used a standard protocol to identify and review the literature and to classify the selected interventions. Twenty-seven interventions were found to have an impact on STD prevention. The study also found that most of the interventions were aimed at adolescents and were implemented in schools. This study aims to improve current interventions in this area and to promote the development and implementation of new programs.

[Evidence-based and promising interventions to prevent unplanned pregnancies: a literature review]. / Interventions validées ou prometteuses en prévention des grossesses non prévues?: synthèse de la littérature.

Despite the widespread use of contraception, the number of unplanned pregnancies in France remains high. This paper reviews the current knowledge of evidence-based programs aimed at preventing unplanned pregnancies. The study used a standard protocol to identify and review the literature and to classify the selected interventions. Sixteen interventions were found to have an effect on contraceptive use, emergency contraception use or the number of unplanned pregnancies. Interventions in this area are aimed at children, adolescents or adult women. The aim of this study is to improve interventions in this area and to promote the development and implementation of new programs.

SARS-CoV-2 seroprevalence in French 9-year-old children and their parents after the first lockdown in 2020.

Introduction: Children have been significantly less affected by COVID-19 than adults and presented with milder and less symptomatic forms of the disease. However, there has been suggestion that children older than 10 years and adolescents exhibits features closer to that of young adults. Most studies combine children in different age-groups and lack sufficient numbers to explore in detail age specificities. We report data on a population-based sample of 2,555 children at the pivotal age of 9 years. Methods: In April 2020, the participants in two French nationwide cohorts of children, Elfe and Epipage2, were invited to take part into an online survey about Covid related symptoms and family life during the lockdown. A second questionnaire was sent on May 5. This questionnaire also proposed to the child included in the cohort and to one of his/her parents to take part into a capillary blood collection for Covid serology. Families who agreed to the serological survey were sent kits for dried blood spots self-sampling (DBS) with instructions. Samples were processed with a commercial Elisa test (Euroimmun®, Lübeck, Germany) to detect anti-SARS-CoV-2 antibodies (IgG) directed against the S1 domain of the spike protein of the virus. Results: Children's acceptance rate for the serological survey was around 60%. 2,555 serological results were analyzed. The weighted prevalence of a positive Elisa Spike serology was 2.8% in 9 yr-old children (95% CI: 1.7%-4.0%). Positive serology was found in 8.6% (7.4%-9.7%) of parents who provided blood. There was a significant association (p < 0.001) between serology of the child and parent from the same household with an odds ratio of 13.8 (7.9-24.2). Discussion: We have shown that 9-yr old children had a lower susceptibility to SARS-Cov2 infection than adults with the initial Chinese strain, similar to younger children and estimated that around 3% of them have developed antibodies against SARS-Cov2 in France after the first wave of the Covid-19 epidemics.

Online self-sampling kits for human immunodeficiency virus and other sexually transmitted infections: Feasibility, positivity rates, and factors associated with infections in France.

BACKGROUND: Men who have sex with men are increasingly diagnosed with sexually transmitted infections (STI) in France. To address this situation, quarterly screening for HIV combined with hepatitis B (HBV) and hepatitis C (HCV), as well as annual screening for C.trachomatis (CT) and N.gonorrhoeae (NG) are recommended. The MemoDepistages program offered an at-home screening solution for these infections. This study describes the feasibility of this screening process, the rate of positive test results, and the factors associated with positivity. METHODS: Participants were recruited online. Laboratories verified the quantity and quality of the samples. Logistic regression was used to determine the associated factors for infection. RESULTS: Overall, 1556 out of 1908 (81.6%) blood samples were tested for at least HIV. A total of eight participants (0.5%) were newly diagnosed with HIV and four with HCV (0.3%). No new infection was confirmed for HBV. Overall positivity was 9.3% for CT and 9.6% for NG. The highest positivity was reported in rectal swabs for CT (7.3%) and in pharyngeal swabs for NG (7.2%). Factors associated with extragenital CT/NG were age under 30 years (for pharyngeal and rectal infections) and having at least 10 partners in the past 6 months (p<0.001) (for pharyngeal infections only). CONCLUSIONS: The self-sampling kit for multiple STIs can perform comprehensive tests and identify new infections in young people, especially in extragenital sites.

Trends in social exposure to SARS-Cov-2 in France. Evidence from the national socio-epidemiological cohort-EPICOV.

BACKGROUND: We aimed to study whether social patterns of exposure to SARS-CoV-2 infection changed in France throughout the year 2020, in light to the easing of social contact restrictions. METHODS: A population-based cohort of individuals aged 15 years or over was randomly selected from the national tax register to collect socio-economic data, migration history, and living conditions in May and November 2020. Home self-sampling on dried blood was proposed to a 10% random subsample in May and to all in November. A positive anti-SARS-CoV-2 ELISA IgG result against the virus spike protein (ELISA-S) was the primary outcome. The design, including sampling and post-stratification weights, was taken into account in univariate and multivariate analyses. RESULTS: Of the 134,391 participants in May, 107,759 completed the second questionnaire in November, and respectively 12,114 and 63,524 were tested. The national ELISA-S seroprevalence was 4.5% [95%CI: 4.0%-5.1%] in May and 6.2% [5.9%-6.6%] in November. It increased markedly in 18-24-year-old population from 4.8% to 10.0%, and among second-generation immigrants from outside Europe from 5.9% to 14.4%. This group remained strongly associated with seropositivity in November, after controlling for any contextual or individual variables, with an adjusted OR of 2.1 [1.7-2.7], compared to the majority population. In both periods, seroprevalence remained higher in healthcare professions than in other occupations. CONCLUSION: The risk of Covid-19 infection increased among young people and second-generation migrants between the first and second epidemic waves, in a context of less strict social restrictions, which seems to have reinforced territorialized socialization among peers.

Antibody status and cumulative incidence of SARS-CoV-2 infection among adults in three regions of France following the first lockdown and associated risk factors: a multicohort study.

BACKGROUND: We aimed to estimate the seropositivity to anti-SARS-CoV-2 antibodies in May-June 2020 after the first lockdown period in adults living in three regions in France and to identify the associated risk factors. METHODS: Between 4 May 2020 and 23 June 2020, 16 000 participants in a survey on COVID-19 from an existing consortium of three general adult population cohorts living in the Ile-de-France (IDF) or Grand Est (GE) (two regions with high rate of COVID-19) or in the Nouvelle-Aquitaine (NA) (with a low rate) were randomly selected to take a dried-blood spot for anti-SARS-CoV-2 antibodies assessment with three different serological methods (ClinicalTrial Identifier #NCT04392388). The primary outcome was a positive anti-SARS-CoV-2 ELISA IgG result against the spike protein of the virus (ELISA-S). Estimates were adjusted using sampling weights and post-stratification methods. Multiple imputation was used to infer the cumulative incidence of SARS-CoV-2 infection with adjustments for imperfect tests accuracies. RESULTS: The analysis included 14 628 participants, 983 with a positive ELISA-S. The weighted estimates of seropositivity and cumulative incidence were 10.0% [95% confidence interval (CI): 9.1%, 10.9%] and 11.4% (95% CI: 10.1%, 12.8%) in IDF, 9.0% (95% CI: 7.7%, 10.2%) and 9.8% (95% CI: 8.1%, 11.8%) in GE and 3.1% (95% CI: 2.4%, 3.7%) and 2.9% (95% CI: 2.1%, 3.8%) in NA, respectively. Seropositivity was higher in younger participants [odds ratio (OR) = 1.84 (95% CI: 1.79, 6.09) in <40 vs 50-60 years old and OR = 0.56 (95% CI: 0.42, 0.74) in ≥70 vs 50-60 years old)] and when at least one child or adolescent lived in the same household [OR = 1.30 (95% CI: 1.11, 1.53)] and was lower in smokers compared with non-smokers [OR = 0.71 (95% CI: 0.57, 0.89)]. CONCLUSIONS: Seropositivity to anti-SARS-CoV-2 antibodies in the French adult population was ≤10% after the first wave. Modifiable and non-modifiable risk factors were identified.

Innovative Approach for Enhancing Testing of HIV, Hepatitis B, and Hepatitis C in the General Population: Protocol for an Acceptability and Feasibility Study (BaroTest 2016).

BACKGROUND: Despite substantial screening for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) infections in France, a great number of infected persons remain undiagnosed. In this context, Santé publique France experimented with a new screening approach for HBV, HCV, and HIV infection, based on home self-sampling using dried blood spot (DBS) for blood collection. OBJECTIVE: The objectives of the BaroTest study were to assess the acceptability and feasibility of this approach and to update the prevalence estimates of HBV, HCV, and HIV infections in the general population. METHODS: Participants were enrolled using the 2016 Health Barometer, a national cross-sectional telephone survey based on a large representative sample of the general population aged 15 to 75 years (N=15,000). Upon completion of the questionnaire, any participant in the Health Barometer aged 18 to 75 years, having medical health insurance, and not under guardianship was invited to receive a self-sampling kit delivered by standard postal mail and to return the DBS card to the laboratory. The laboratory was then responsible for reporting the results to the participants. Acceptability of the protocol was based on the percentage of eligible individuals agreeing to receive the self-sampling kit, on the proportion of people returning the DBS card, and on the proportion of participants out of the total eligible population. The feasibility of the approach was based on the number of participants with adequately filled blood spots and the number of participants with blood spots for which at least one virological analysis could be performed. A complex system of reminders was implemented to increase the participation rate. Accordingly, we assumed that 35.00% (4900/14,000) of eligible persons would accept and return their DBS card. As the highest expected prevalence was for HBV infection, estimated at 0.65% in 2004, 5000 persons would make it possible to estimate this prevalence with an accuracy of approximately 0.22%. All indicators can be analyzed according to the characteristics of the participants collected in the Health Barometer questionnaire. BaroTest was approved by the French Ethics Committee (November 11, 2015) and the Commission on Information Technology and Liberties (December 24, 2015). The study has been registered by the French medical authority under number 2015-A01252-47 on November 10, 2015. RESULTS: The results on acceptability and feasibility are expected in the last quarter of 2018 and those on the prevalence estimates in the first semester of 2019. CONCLUSIONS: The BaroTest results will help to inform new strategies for HIV, HBV, and HCV screening, and the Health Barometer provides a reliable updated assessment of the burden of HBV, HCV, and HIV infections in the general population in France while reducing the costs typically associated with this type of research. REGISTERED REPORT IDENTIFIER: RR1-10.2196/9797.