Can the tuberculosis BCG vaccine provide protection against respiratory infections, including COVID-19, in older adults? A recent multicenter clinical trial aimed to answer this question by randomly assigning 2,014 individuals aged 60 years or older to receive either the BCG vaccine or a placebo. The primary endpoint was the cumulative incidence of respiratory tract infections requiring medical intervention over a 12-month period, while secondary endpoints included the incidence of COVID-19 and the effect of BCG vaccination on immune responses.
The study found that BCG vaccination did not have a significant impact on the incidence of respiratory tract infections, including COVID-19, compared to the control group. However, BCG vaccination was associated with enhanced cytokine responses after influenza and SARS-CoV-2 stimulation and induced stronger antibody titers after COVID-19 infection.
The BCG vaccine has been proposed as a potential preventive strategy against COVID-19 due to its ability to provide heterologous protection against nontuberculous infections. However, the results of this clinical trial suggest that BCG vaccination may not be effective in preventing respiratory infections in older adults.
Despite this, the study's findings on the vaccine's ability to enhance immune responses to viral infections such as influenza and COVID-19 are promising. This suggests that the BCG vaccine could potentially play a role in boosting the immune system's ability to fight off viral infections in older adults.