Neutralizing antibodies response to SARS-CoV-2 are persistent 9 months post symptom onset in mild or asymptomatic patients

Bylicki, Olivier; Delarbre, David; Mayet, Aurélie; Ferrier, Audrey; Perisse, Anne; Malle, Carine; Cobola, Jacques; Bronstein, Antoine; Menoud, Nastasia; Valero-Biance, Elodie; Ferraris, Olivier; Janvier, Frédéric; Tournier, Jean-Nicolas

Objective A better understanding of immune response against SARS-CoV-2 infection is critical to predict its dynamics within general population and its impact on vaccination strategy. We assessed both neutralizing antibody (Nab) activity persistence and SARS-CoV-2 serology in serum samples of mild and asymptomatic patients nine months post symptom onset (PSO) in a primary care context among immunocompetent adults. Methods A longitudinal cohort of crewmembers (CM) exposed to COVID-19 during the SARS-CoV-2 outbreak on the French aircraft carrier in April 2020 was created. CM infected with COVID-19 and having a positive serology at the end of quarantine were tested at 9-months PSO. Samples were collected at 18 and 280-days PSO. For each patient, both serology and serum viral neutralizing activity were performed. Results We analyzed 86 CM. Samples were collected at 18 and 280-days PSO. The seroconversion rate was 100% and 93% (82/86) at 18 and 280 days, respectively, while 72.7% of patients exhibited Persistent Nab at 9 months, regardless of disease severity. Conclusion Nab persists up to 9 months following asymptomatic/mild COVID-19 among young adults regardless of serology results at that time.