Seven-month kinetics of SARS-CoV-2 antibodies and role of pre-existing antibodies to human coronaviruses

Ortega, Natalia; Ribes, Marta; Vidal, Marta; Rubio, Rocío; Aguilar, Ruth; Williams, Sarah; Barrios, Diana; Alonso, Selena; Hernández-Luis, Pablo; Mitchell, Robert A.; Jairoce, Chenjerai; Cruz, Angeline; Jimenez, Alfons; Santano, Rebeca; Méndez, Susana; Lamoglia, Montserrat; Rosell, Neus; Llupià , Anna; Puyol, Laura; Chi, Jordi; Melero, Natalia Rodrigo; Parras, Daniel; Serra, Pau; Pradenas, Edwards; Trinité, Benjamin; Blanco, Julià ; Mayor, Alfredo; Barroso, Sonia; Varela, Pilar; Vilella, Anna; Trilla, Antoni; Santamaria, Pere; Carolis, Carlo; Tortajada, Marta; Izquierdo, Luis; Angulo, Ana; Engel, Pablo; García-Basteiro, Alberto L.; Moncunill, Gemma; Dobaño, Carlota

Unraveling the long-term kinetics of antibodies to SARS-CoV-2 and the individual characteristics influencing it, including the impact of pre-existing antibodies to human coronaviruses causing common cold (HCoVs), is essential to understand protective immunity to COVID-19 and devise effective surveillance strategies. IgM, IgA and IgG levels against six SARS-CoV-2 antigens and the nucleocapsid antigen of the four HCoV (229E, NL63, OC43 and HKU1) were quantified by Luminex, and antibody neutralization capacity was assessed by flow cytometry, in a cohort of health care workers followed up to 7 months (N = 578). Seroprevalence increases over time from 13.5% (month 0) and 15.6% (month 1) to 16.4% (month 6). Levels of antibodies, including those with neutralizing capacity, are stable over time, except IgG to nucleocapsid antigen and IgM levels that wane. After the peak response, anti-spike antibody levels increase from ~150 days post-symptom onset in all individuals (73% for IgG), in the absence of any evidence of re-exposure. IgG and IgA to HCoV are 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.