The persistence of SARS-CoV-2 neutralizing antibodies after COVID-19: A one-year observation. Is a SARS-CoV-2 vaccination booster dose necessary?

INTRODUCTION: The aim of this study was to investigate the persistence of SARS-CoV-2 neutralizing antibodies (NAbs) one year after contracting COVID-19. MATERIAL AND METHODS: The study included 38 patients – 34 men and 4 women – suffering from COVID-19 between March 15 and May 26, 2020. The median age in the group was 31 years, ranging from 22 to 67 years. The levels of neutralizing antibodies were measured at three time-points – baseline, 6 months, and 12 months. The primary endpoint was a post-infection positive result for NAbs (> 15 AU/ml; Liaison SARS-CoV-2 S1/S2 IgG quantitative test) 12 months after infection. RESULTS: The median level of NAbs after 12 months was 26.5 AU/ml. At the end of observation (12 months), 21 of the 38 patients had a NAb level of >15 AU/ml (positive). The median antibody half-life was 5.8 months. CONCLUSIONS: A high percentage of the patients maintained positive levels of antibodies 6 and 12 months after COVID-19 infection. The dynamics of the antibody level decline suggests the need for booster vaccination at least once a year.