ABSTRACT
Introduction Bacillus Calmette-Guérin (BCG) vaccine was considered as a tool against SARS-CoV-2 based on the concept of trained immunity, which could be useful against emerging pathogens. Methods A multicenter double-blinded randomized clinical trial recruited health care workers (HCW) in Brazil. The incidence rates of COVID-19, clinical manifestations, absenteeism, and adverse events among HCW receiving BCG vaccine (Moreau or Moscow strains) or placebo were compared. BCG vaccine-mediated immune response before and after implementing specific vaccines for COVID-19 (CoronaVac® or CovishieldTM) was analyzed. Cox proportional hazard and linear mixed effect modelling were used. Results 264 volunteers were included for analysis (BCG=134 and placebo=130). Placebo group presented a COVID-19 cumulative incidence of 0.75% versus 0.52% of BCG. Moreau strain also presented a higher incidence rate (1.60% x 0.22%). BCG did not show a protective hazard ratio against COVID-19. In addition, the log(IgG) level against SARS-CoV-2 presented a higher increase in the BCG group, whether or not participants had COVID-19, but also without statistical significance. Conclusion Our results suggest a BCG's tendency of protection against SARS-CoV-2 and higher IgG levels when compared to placebo. The clinical trial was registered at https://clinicaltrials.gov/ (NCT04659941).
ABSTRACT
OBJECTIVES: Evatuate if Bacillus Calmette-Guérin (BCG) vaccine could be used as a tool against SARS-CoV-2 based on the concept of trained immunity. METHODS: A multicenter, double-blinded, randomized clinical trial recruited health care workers (HCWs) in Brazil. The incidence rates of COVID-19, clinical manifestations, absenteeism, and adverse events among HCWs receiving BCG vaccine (Moreau or Moscow strains) or placebo were compared. BCG vaccine-mediated immune response before and after implementing specific vaccines for COVID-19 (CoronaVac or COVISHIELD) was analyzed. Cox proportional hazard and linear mixed effect modeling were used. RESULTS: A total of 264 volunteers were included for analysis (BCG = 134 and placebo = 130). The placebo group presented a COVID-19 cumulative incidence of 0.75% vs 0.52% of BCG. The Moreau strain also presented a higher incidence rate (1.60% × 0.22%). BCG did not show a protective hazard ratio against COVID-19. In addition, the log (immunoglobulin G) level against SARS-CoV-2 presented a higher increase in the BCG group, whether or not participants had COVID-19, but also without statistical significance. CONCLUSION: Our results suggest that BCG has a tendency of protection against SARS-CoV-2 and higher immunoglobulin G levels than placebo. The clinical trial was registered at https://clinicaltrials.gov/ (NCT04659941).