Seven-month kinetics of SARS-CoV-2 antibodies and protective role of pre-existing antibodies to seasonal human coronaviruses on COVID-19

Ortega, N.; Ribes, M.; Vidal, M.; Rubio, R.; Aguilar, R.; Williams, S.; Barrios, D.; Alonso, S.; Hernandez-Luis, P.; Mitchell, R. A.; Jairoce, C.; Cruz, A. M.; Jimenez, A.; Santano, R.; Mendez, S.; Lamoglia, M.; Rosell, N.; Llupia, A.; Puyol, L.; Chi, J.; Rodrigo, N.; Parras, D.; Serra, P.; Mayor, A.; Barroso, S.; Varela, P.; Vilella, A.; Trilla, A.; Santamaria, P.; Carolis, C.; Tortajada, M.; Izquierdo, L.; Angulo, A.; Engel, P.; Garcia-Basteiro, A.; Moncunill, G.; Dobano, C.

Unraveling long-term kinetics of antibodies to SARS-CoV-2 and the factors influencing its course, like prior antibody levels to human coronaviruses causing common cold (HCoVs), is essential to understand protective immunity and effective surveillance strategies. Antibody levels against six SARS-CoV-2 and four HCoV antigens were quantified by Luminex, and antibody neutralization capacity was assessed by flow cytometry in a cohort of health care workers followed-up for 6 months. Seroprevalence increased over time from 13.5% (month 0) and 15.6% (month 1), to 16.4% (month 6). Levels of antibodies were stable over time, except IgG against nucleocapsid antigen and IgM levels that waned. After the peak response, anti-spike antibody levels increased from ~150 days post-symptom onset in all individuals (73% for IgG), in the absence of any evidence of re-exposure. The neutralizing capacity of antibodies was maintained. Pre-existing antibodies to alpha-HCoV were lower in individuals who subsequently seroconverted for SARS-CoV-2. IgG and IgA to HCoV were significantly higher in asymptomatic than symptomatic seropositive individuals. Thus, pre-existing cross-reactive HCoVs antibodies could have a protective effect against SARS-CoV-2 infection and COVID-19 disease.