Epidémiolgie - Santé Publique (Epidemiology - Public Health) - Dynamique de l'épidémie à SARS-CoV-2 à Conakry, Guinée (COVEPIGUI) SARS-CoV-2 outbreak dynamics in Conakry, Guinea (COVEPIGUI)

Objectives Primary objective The main objective of the study is to describe the dynamics of the SARS-CoV-2 epidemic in the city of Conakry, represented by the evolution over time of seroprevalence stratified by age group (under 15 years, 15-39 years and 40 years or more). Secondary objectives 1. To estimate the proportion of asymptomatic or pauci-symptomatic cases among participants with positive serology for SARS-CoV-2 infection 2. To estimate seroprevalence overall and by age group in each survey 3. To estimate in each survey the number of confirmed or probable cases of SARS-CoV-2 infection among seropositive participants. 4. To analyze the relationship between demographic and clinical characteristics, possible contact with a confirmed or probable case, and SARS-CoV-2 serostatus. 5. Retrospectively analyse of the sociological conditions of the contamination among serologically confirmed individuals. Methodology: Three repeated general population surveys spaced 6 weeks apart. For each survey, we will use a two-stage random sampling design. The aim is to obtain a representative sample of the population of Conakry. Each survey is independent of the other. Estimated enrolment 1400 individuals per survey The calculation of the sample size is based on the hypothesis of a 10% difference in seroprevalence per age group between the first and second survey, using participants aged 40 years and older because they represent the smallest age group (17.5% of Conakry residents). Assuming an intraclass correlation coefficient (ICC) of 0.10, a participation rate of 90%, an average of one individual aged 40 and over per household visited (on average 6 residents per household in Conakry), with a confidence level α=0.05 and a power of 0.8 (β=0.2), 380 residents aged 40 and over, rounded up to 400 households, or 40 clusters of 10 households, will have to be included in each survey. To balance the groups, individuals under 40 years of age will be invited to participate in the study in only 50% of households. In total, 1400 individuals to participate (400 aged 40 and over + 5 residents under 40 in half of the 400 selected households). Outcomes Primary outcome: The difference in seroprevalence between two surveys Secondary outcomes:  The proportion of symptomatic cases defined as the presence of symptoms of SARS-CoV-2 infection since the beginning of the year among participants with positive SARS-CoV-2 serology : o Fever o Fatigue o Cough (dry) o Rhinitis o Sore throat o Difficulty breathing o Chest pain o Muscle aches and pains o Nausea/Vomiting o Dermatological signs, anosmia, dysgeusia o Asthenia o Anorexia  The proportion of asymptomatic cases among participants with positive CoV-2 SARS serology.  Seroprevalence defined as the proportion of participants by age group with IgG antibodies to SARS-CoV-2.  The number of cases previously confirmed by PCR.  The number of cases previously classified as probable ( https://www.who.int/publications-detail/global-surveillance-for-human-infection-with-novel-coronavirus-(2019-ncov).  Contact with a patient with suspected or confirmed SARS-CoV-2 infection.  The proportion of individuals who visited a health care provider for one or more of these symptoms.  Among individuals with a positive serology, the proportion who were diagnosed with CA-MRSA-CoV-2 confirmed infection by PCR, the proportion who were diagnosed with probable infection and the proportion who were undiagnosed. Eligibility Inclusion criteria:  For adult participants (age ≥ 18 years old): Agree to participate in the study and sign the consent prior to any intervention.  For participants under the age of majority (between 10 and 17 years of age): Informed consent signed by at least one parent or legal guardian authorizing the child's participation in the study and the child's written consent to participate in the study.  For minor participants (age < 10 years): Informed consent signed by at least one parent or legal guardian authorizing the child's participation in the study. Non-inclusion criteria:  Inability to comply with study requirements and procedures in the opinion of the investigator;  Inability to consent. Statistical methods The household questionnaire will be used for descriptive analyses on the included population and those who did not participate in the serological survey. For each participant, several dimensions will be considered. The descriptive analyses will be weighted to take into account the probability of selection for cluster sampling and will be presented with a 95% confidence interval. Simple t-test and Pearson chi2 statistics will be used to compare the continuous and categorical descriptive results, respectively. Results will be calculated with the corresponding 95% confidence intervals and stratified by age group and sex. The actual intra-family correlation coefficient will be calculated at the end of the first survey. Serological results will be stratified by age and weighted to take into account the sampling effect. Multivariate logistic models will assess the association between seroprevalence and risk factors in each study. After the first survey, a conventional cross-sectional analysis will be conducted followed by an incremental approach by pooling data from subsequent surveys and introducing a covariate coding for prevalence at each survey. Spatial heterogeneity will be taken into account. The dynamics of the epidemic will be modelled using generalized linear models . In addition, the epidemic diffusion models that will be available, published by other teams, will be applied to the data in order to estimate the diffusion parameters observed in Conakry (cumulative incidence, doubling time, spatial variability of transmission). Estimated planning Study start date: Third quarter 2020 Enrolment period: 4 months Subject participation duration: 1 day Total study duration: 12 months Estimated study completion date: July 2021