ABSTRACT
Background: SARS-CoV-2 induces a humoral response with seroconversion occurring within the first weeks after COVID-19 disease. Those antibodies exert a neutralizing activity against SARS-CoV-2, whose evolution overtime after COVID-19 is however unknown.Methods: In this monocentric prospective study, sera of 107 patients hospitalized with COVID-19 were collected at 3 months and 6 months post-infection. We performed quantitative neutralization experiments on top of high-throughput serological assays evaluating anti-Spike (S) and anti-Nucleocapsid (NP) IgG.Findings: Levels of sero-neutralization decreased significantly over study time, as well as IgG rates. After 6 months, 2.8% of the patients had a negative serological status for both anti-S and anti-NP IgG. However, all sera had a persistent and effective neutralizing effect on SARS-CoV-2 neutralizing assays. IgG levels correlated with sero-neutralization and this correlation was stronger for anti-S than for anti-NP antibodies. The level of sero-neutralization quantified at 6 months correlated with markers of initial severity, notably admission in intensive care units and the need for mechanical invasive ventilation.Interpretation: Decrease of IgG rates and serological assays becoming negative did not imply loss of neutralizing capacity in our patients. Those results are encouraging and in favor of sustained humoral response for at least 6 months in patients previously hospitalized for COVID-19, which will have to be considered in global deployment of vaccination strategy.Trial Registration: The French Covid cohort (NCT04262921)Funding Statement: The French COVID cohort is funding by the REACTing (REsearch & ACtion emergING infectious diseases) consortium and by a grant of the French Ministry of Health (PHRC n°20-0424).Outside the submitted work, JSH is supported by AP-HP, INSERM, the French National Research Agency (NADHeart ANR-17-CE17-0015-02, PACIFIC ANR-18-CE14-0032-01, CORRECT_LMNA ANR-19-CE17-0013-02), the ERA-Net-CVD (ANR-16-ECVD-0011-03, Clarify project), Fédération Française de Cardiologie, the Fondation pour la Recherche Médicale, and by a grant from the Leducq Foundation (18CVD05), and is coordinating a French PIA Project (2018-PSPC-07, PACIFIC-preserved, BPIFrance) and a University Research Federation against heart failure (FHU2019, PREVENT_Heart Failure). JG reports personal fees from ViiV Healthcare, Gilead Science, Janssen Cilag, and research grants from Gilead Sciences, MSD and ViiV Healthcare, outside the submitted work.Declaration of Interests: Authors have nothing to disclose. There are no relationships with industry.Ethics Approval Statement: The French Covid cohort (NCT04262921) is a prospective multi-center observational cohort sponsored by Inserm which was authorized by the French Ethics Committee CPP Ile-de-France VI (ID RCB:2020-A00256-33).