Seroprevalence of IgG Antibodies to SARS-CoV-2 (COVID-19) in Primary Health Care Workers and Their Household Contacts

Plain-language summary

Many uncertainties remain regarding the epidemiological and clinical characteristics of COVID-19, including the number of people exposed to the disease, the persistence of the humoral response and its associated neutralisation capacity in recovered patients, and the long-term health consequences of the infection. The French national COVID-SeroPRIM survey aims to estimate the seroprevalence of IgG antibodies to SARS-CoV-2 in four populations of primary care health professionals: primary care physicians (general practitioners and paediatricians), health professionals working in city pharmacies (pharmacists and compounders) and in dental practices (dentists and dental assistants). Indeed, the majority of published studies target healthcare professionals in hospitals. It is therefore essential to provide new knowledge on the exposure of primary care workers to the virus in order to assess the impact of the pandemic, the level of immunity and the risk factors for exposure to the virus. These data will be very useful for public health decision makers to better adapt health protocols and provide useful information to better guide future vaccination campaigns. Assuming that vaccination against COVID-19 will start in January 2021, data on the vaccination rate of health professionals and their households will also be collected and made available to policy makers in a timely manner. This study will be conducted in collaboration with four primary care research and/or monitoring networks: the Sentinelles network (general practitioners), the Association de Formation Professionnelle en Pédiatrie (Association for Professional Training in Paediatrics), IQVIA (general practitioners and pharmacies), and the Réseau de Recherche Clinique en Odontologie Libérale (ReCOL, dental surgeons) Seroprevalence will be estimated using a high-sensitivity ELISA designed to detect SARS-CoV-2 specific IgG antibodies in humoral fluid and a high-specificity seroneutralisation test to assess seropositivity (i.e. excluding false positive ELISA results due to cross-reactivity with other coronaviruses) and to assess SARS-CoV-2 neutralising antibody levels. These techniques have already been used in two general population cohort studies (SAPRIS-SERO and EpiCoV) with the objective of describing SARS-CoV-2 seroprevalence and risk factors. The secondary objectives of the COVID-SeroPRIM study will be to assess the seroprevalence of IgG antibodies to SARS-CoV-2 in household contacts of health care workers, to identify risk factors for seropositivity to SARS-CoV-2, and to retrospectively describe the symptoms experienced by individuals diagnosed with COVID-19. Due to the use of the same methodology to assess seroprevalence, these results will be broadly complementary and comparable to those of seroepidemiological studies conducted in the general population, such as EpiCOV and SAPRIS-SERO. These surveys (EpiCOV, SAPRIS-SERO and COVID-SeroPRIM) as a whole are based on similar questionnaires and identical serological methods and will provide many health indicators such as the proportion of people who presented symptoms, who consulted for a suspicion of COVID-19, who were screened but also who did not seek care in the recent period. The COVID-SeroPRIM study, by targeting primary care health professionals and their households, will provide data to reinforce the knowledge from SAPRIS-SERO and EpiCOV and to better understand the dynamics of the epidemic in these four populations in order to guide public policy makers. This project has received funding from the French National Research Agency (ANR) as part of the COVID-19 call for research projects, which aims to support urgent and rapid projects whose results could be implemented in society in the coming months. Main objective To estimate the seroprevalence of IgG antibodies to SARS-CoV-2 in four distinct populations of primary care health professionals (general practitioners, paediatricians, health professionals practising in city pharmacies and dental practices) in metropolitan France.

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