ABSTRACT
Introduction: The mRNA COVID-19 BNT162b2 vaccine has successfully reduced the burden of coronavirus disease 2019 (COVID-19). The serum IgG and IgA responses to the vaccine have been extensively reported. Recent studies suggest that mRNA vaccine induces IgG and IgA production (or secretion) from the upper respiratory tract mucosa. Aim(s): To evaluate whether BNT162b2 vaccine provides lower airways protection by inducing IgG and IgA neutralizing antibodies from the lung. Method(s): Prospective observational study in patients undergoing medically indicated bronchoscopy and bronchoalveolar lavage (BAL). Serum, saliva and BAL fluids were collected from the participants in order to assess immunoglobulins targeting the Receptor Binding Domain (RBD) of SARS-CoV-2. The functional neutralization is measured in cultured cells, using SARS-CoV-2 spike pseudotyped reporter particles. Result(s): Serum, saliva and BAL fluid were obtained from 68 individuals (6 unvaccinated, 7 vaccinated with 2 doses, 34 vaccinated with 3 doses, 5 vaccinated with 4 doses, 7 recovered, 6 recovered and vaccinated (1 doses at least)). We have adjusted custom enzyme linked immunoassay to quantify molar equivalents of anti-RBD IgG and IgA in serum, saliva and BAL fluids. We detected and characterized anti-RBD IgG and IgA in serum, saliva and BAL of vaccinated and recovered individuals. Conclusion(s): BNT162b2 mRNA COVID-19 vaccine induces IgG and IgA responses against SARS-CoV-2 in the lungs.