The real seroprevalence of SARS-CoV-2 in France and its consequences for virus dynamics.

Abstract The SARS-CoV-2 virus has spread world-wide since December 2019, affecting millions of people and killing thousands. The recent use of serological tests to measure the effective seroprevalence of SARS-CoV-2 in the general population has led us to assess the consequences of a much lower than expected seroprevalence on the real dynamics of the virus in the population. Our prediction models assumed a 4.2% seroprevalence in Occitania and it has turned out to be only 1.3% (CI 95%: 0.6% - 2.6%, binomial method). This implies a lower than expected virus transmission rate , which may be due to infectivity varying with the patient’s symptoms or to a constraint due to an uneven population geographical distribution.