One of the oldest vaccines could protect us against our newest infectious disease, COVID-19. The vaccine has been given to babies to protect them against tuberculosis for almost a century, but has been shown to shield them from other infections too, prompting scientists to investigate whether it can protect against the coronavirus.
This Bacille Calmette-Guérin (BCG) vaccine, named after two French microbiologists, consists of a live weakened strain of Mycobacterium bovis, a cousin of M. tuberculosis, the bacterium that causes tuberculosis.
[R]esearchers decided to compare data from countries with and without mandatory BCG vaccination to see if immunization policies are linked to the number or severity of COVID-19 infections. A handful of preprint publications in the last two months noted that countries with an ongoing BCG vaccination program are experiencing lower death rates from COVID-19 than those without.
One study, for instance, found that mandatory BCG was associated with a significantly slower climb in both confirmed cases and deaths during the first 30-day period of an outbreak.
In the absence of clinical trial data, the World Health Organization does not recommend BCG for the prevention of COVID-19. There is concern that people might jump the gun and decide BCG is effective before the trial results come out.