In the early days of the Covid pandemic, scientists launched trials to see whether a century-old vaccine might be able to protect people by bolstering their immune systems.
The tuberculosis vaccine was developed in the early 1900s, called the Bacillus-Calmette-Guerin vaccine. It has long been known to have broad effects on the immune system and is still given to infants in the developing world and in countries where TB is prevalent.
Scientists observed a long time ago that the vaccine seems to train the immune system to respond to a variety of infectious diseases, including viruses, bacteria, and parasites. It also reduces infant mortality.
As new pandemic threats are emerging and re-emerging, the potential of the old vaccine to provide a measure of universal protection against infectious diseases has gained renewed interest among scientists and experts.
It comes as Covid continues to evolve, and threats like monkeypox and polio re-emerge.
The results of clinical trials conducted during the pandemic are now coming in, and the findings are encouraging. The latest results were published this week in Cell Medicine Reports, and come from a trial initiated before Covid emerged.
It was designed to see whether multiple injections of the TB vaccination could benefit people with Type 1 diabetes who are highly susceptible to infection.
When the pandemic began in January 2020, investigators started tracking Covid infections among the trial’s 144 participants. All of them had Type 1 diabetes. Two-thirds had received at least three B.C.G. Doses before the pandemic. The remaining one-third had multiple placebo injections.
While the scientists are still evaluating the vaccine’s long-term effects on Type 1 diabetes itself, they commissioned an independent group to look at Covid infections among the participants for 15 months, before any got a Covid vaccination.
The results were dramatic: only one — or slightly more than 1 percent — of the 96 people who had received the B.C.G. doses developed Covid, compared with six — or 12.5 percent — of the 48 participants who received dummy shots.