IMPACTO DA VACINAÇÃO PRÉVIA COM BCG NA RESPOSTA ANTI-SPIKE IGG EM PROFISSIONAIS DE SAÚDE IMUNIZADOS COM DIFERENTES VACINAS CONTRA COVID-19

Abstract

COVID-19 is an infectious disease caused by the SARS-CoV-2 coronavirus, with a global impact. Several research studies have been conducted to find vaccines to prevent the infection, among which AstraZeneca, CoronaVac, and BNT162b2 have been administered in Brazil. The Bacille Calmette-Guérin (BCG) vaccine, used against tuberculosis, has shown in studies to offer protection against non-specific pathogens, activating macrophages, phagocytes and pro-inflammatory cytokines, possessing antiviral activity. This non-specific antiviral activity led to an interest in investigating whether this vaccine could provide some protection against SARS-CoV-2. Therefore, the objective of this study was to quantify seroconversion and antibody levels produced by vaccines available in the Brazilian market, considering the influence of BCG vaccination. A total of 874 healthcare workers over 18 years of age were selected and divided into groups for the AZD1222 vaccine (n=592), CoronaVac (n=264), and Pfizer (n=18), each with subdivisions between those who received the placebo and those who received BCG. A quantitative and qualitative test of anti-spike IgG was performed using a chemiluminescent microparticle immunoassay on serum samples collected 28 days after vaccination. The group that received the Pfizer vaccine had a reduced number of participants, and therefore, their results were excluded from the statistical analysis. The study found that the levels of anti-spike IgG antibodies were two times higher in the AZD1222 vaccine compared to CoronaVac (geometric mean ratio (GMR) 2.58, 95% confidence interval (CI)) with two doses. When comparing two doses of CoronaVac with one dose of AZD1222, the result was similar (GMR 0.99, 95% CI). The presence of BCG (BCG group n=435; saline placebo n=439) did not induce an increase in antibodies against SARS-CoV-2 in both groups (AZD1222 p=0.38; CoronaVac p=0.76). Therefore, it is concluded that the presence of the BCG vaccine did not increase protection mediated by antibodies against COVID-19, and the AZD1222 vaccine induced twice as many antibodies as the CoronaVac vaccine.