Journal of Infectious Diseases 2020

SARS-CoV-2 seroprevalence and antibody kinetics among health care workers in a Spanish hospital after three months of follow-up.

Moncunill G, Mayor A, Santano R, Jiménez A, Vidal M, Tortajada M, Sanz S, Méndez S, Llupià A, Aguilar R, Alonso S, Barrios D, Carolis C, Cisteró P, Chóliz E, Cruz A, Fochs S, Jairoce C, Hecht J, Lamoglia M, Martínez MJ, Moreno J, Mitchell RA, Ortega N, Pey N, Puyol L, Ribes M, Rosell N, Figueroa-Romero A, Sotomayor P, Torres S, Williams S, Barroso S, Vilella A, Trilla A, Varela P, Dobaño C, García-Basteiro AL


"At the COVID-19 pandemic peak in Spain, prevalence of SARS-CoV-2 infection in a cohort of 578 randomly selected health care workers (HCW) from Hospital Cl\xC3\xADnic de Barcelona was 11.2%."


A follow-up survey one month later (April-May 2020) measured infection by rRT-PCR and IgM, IgA, IgG to the receptor-binding domain of the spike protein by Luminex. Antibody kinetics, including IgG subclasses, was assessed till month 3.


At month 1, the prevalence of infection measured by rRT-PCR and serology was 14.9% (84/565) and the seroprevalence 14.5% (82/565). We found 25 (5%) new infections in participants without previous evidence of infection (501). IgM, IgG and IgA levels declined in 3 months (antibody decay rates 0.15 (95% CI, 0.11; 0.19), 0.66 (95% CI, 0.54; 0.82), 0.12 (95% CI, 0.09; 0.16), respectively), and 68.33% of HCW had seroreverted for IgM, 3.08% for IgG, and 24.29% for IgA. The most frequent subclass responses were IgG1 (highest levels) and IgG2, followed by IgG3, and only IgA1 but no IgA2 was detected.


Continuous and improved surveillance of SARS-CoV-2 infections in HCW remains critical, particularly in high-risk groups. The observed fast decay of IgA and IgM levels have implications for seroprevalence studies using these isotypes.