biostudies-literatureUnknown75Moncunill G<h4>Background</h4>Two doses of mRNA vaccination have shown >94% efficacy at preventing COVID-19 mostly in naïve adults, but it is not clear if the second dose is needed to maximize effectiveness in those previously exposed to SARS-CoV-2 and what other factors affect responsiveness.<h4>Methods</h4>We measured IgA, IgG and IgM levels against SARS-CoV-2 spike (S) and nucleocapsid (N) antigens from the wild-type and S from the Alpha, Beta and Gamma variants of concern, after BNT162b2 (Pfizer/BioNTech) or mRNA-1273 (Moderna) vaccination in a cohort of health care workers (N=578). Neutralizing capacity and antibody avidity were evaluated. Data were analyzed in relation to COVID-19 history, comorbidities, vaccine doses, brand and adverse events.<h4>Findings</h4>Vaccination induced robust IgA andEBioMedicine103805https://www.ebi.ac.uk/biostudies/studies/S-EPMC8752368biostudies-literatureDeterminants of early antibody responses to COVID-19 mRNA vaccines in a cohort of exposed and naive healthcare workers.PMC8752368Vilella AGarcia-Basteiro ALMoncunill GRibes MOrtega NLlupia ARodrigo Melero NVarela PAguilar RRubio RMolina MJPuyol LEngel PTortajada MCarolis CAngulo ARodo PCastellana CMitchell RAMendez SDobano CBarroso SMayor AIzquierdo LTrilla AJimenez ABarrios DSalmeron GVidal MHernandez-Luis PfalseDeterminants of early antibody responses to COVID-19 mRNA vaccines in a cohort of exposed and naive healthcare workers.<h4>Background</h4>Two doses of mRNA vaccination have shown >94% efficacy at preventing COVID-19 mostly in naïve adults, but it is not clear if the second dose is needed to maximize effectiveness in those previously exposed to SARS-CoV-2 and what other factors affect responsiveness.<h4>Methods</h4>We measured IgA, IgG and IgM levels against SARS-CoV-2 spike (S) and nucleocapsid (N) antigens from the wild-type and S from the Alpha, Beta and Gamma variants of concern, after BNT162b2 (Pfizer/BioNTech) or mRNA-1273 (Moderna) vaccination in a cohort of health care workers (N=578). Neutralizing capacity and antibody avidity were evaluated. Data were analyzed in relation to COVID-19 history, comorbidities, vaccine doses, brand and adverse events.<h4>Findings</h4>Vaccination induced robust IgA and2022-01-01T00:00:00Z2022 Jan2025-04-22T13:16:36.909Z2025-02-18T23:26:45.663ZS-EPMC87523683503296110.1016/j.ebiom.2021.103805