BCG vaccination at birth confers no benefit for COVID-19 in midlife

Receipt of the Bacille Calmette-Guérin (BCG) tuberculosis vaccine at birth does not appear to protect against the development of the novel coronavirus disease (COVID-19) in middle-aged individuals, a study reports.

The BCG vaccine provides immunity against respiratory infections, with recent studies reporting that countries with universal BCG childhood vaccination policies tend to be less affected by the COVID-19 pandemic, the researchers noted.

In the current study, the researchers investigated a rare nationwide natural experiment conducted in Sweden in 1975, where discontinuation of BCG vaccination led to a dramatic drop in the BCG coverage rate thereafter, in relation to the incidence of COVID-19 and related hospitalizations.

The analysis included 1,026,304 and 1,018,544 individuals born before and just after 1975, respectively. Based on nationwide reports on the vaccination status of children aged <7 years, 92 percent of children born in 1974 got vaccinated as opposed to only 2 percent of those born after the 1975 change in policy.

BCG vaccination at birth did not exert a strong protective effect on the risk of developing COVID-19 (odds ratio [OR], 1.0005, 95 percent confidence interval [CI], 0.8130–1.1881) or COVID-19–related hospitalizations (OR, 1.2046, 95 percent CI, 0.7532–1.6560) at least in middle-aged individuals.

The present data suggest that the differences in the severity of the pandemic across countries cannot be attributed to BCG childhood vaccination policies, as had been hypothesized by prior studies, according to the researchers. [Med Hypotheses 2020;142:109816; Allergy 2020;doi:10.1111/all.14344]