Gabon is the 3rd country most affected by COVID-19 behind Cameroon and Democratic Republic of Congo in Central Africa, with 8860 cases and 54 deaths in critically ill patients, since the first confirmed case of COVID-19 on the 10th of March 2020 (https://africacdc.org/covid-19/). Most of the individuals infected by SARS-CoV-2 are asymptomatic and they represent a major source of viral spread. To date, African countries have been less affected by deaths caused by the Covid-19 pandemic compared to other countries. It is currently unknown why Africa has avoided more deaths and appears to not simply be due to a lack of testing, since the overall death rate has not increased. Better quality data on seroprevalence in different African regions and proven explanations of the differences between Africa and other continents, are urgently needed. The aim of this study is to learn about the proportion of people after a first pic of transmission, who have been exposed to COVID-19 in Gabon by testing for plasma antibodies to the SARS-CoV-2 virus.

The overall goal of this study is to examine the trend of specific anti-SARS-CoV-2 antibodies in Gabonese population.

Based on its technical capacities (ELISA bench and multiparametric flow cytometer), we will provide evident data on the immune responses in Covid-19 infected patients. The quantification of antibodies against SARS-CoV-2 recombinant protein will be done by ELISA using Wantai ELISA total Ab. Meanwhile, data on clinical status will be recorded and classified using WHO patient form. Data obtained will be analyzed by a statistician based at CERMEL using robust models in compliance with the type of data generated.

Inclusion Criteria:

• Persons of both sexes aged one year and older and residing for more than three months in the study area are eligible to participate in the study

Exclusion Criteria:

• Any person not residing in the locality surveyed or any person residing for less than three months. Refusal to give informed consent and contraindication to venipuncture venipuncture.

A total of 3455 people living in Gabon, aged from 1 year, and above will be stratified by age and included in this study