Why a Century-Old Vaccine Offers New Hope Against Pathogens - The New York Times

tuberculosis vaccine may protect against Covid-19 and other infections by broadly bolstering the immune system.

In the early days of the Covid-19 pandemic, when prevention seemed light years away, several scientists launched trials to see whether a tuberculosis vaccine developed in the early 1900s might protect people by bolstering the immune system.

The Bacillus-Calmette-Guerin vaccine 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.

All of them had Type 1 diabetes; two-thirds had received at least three B.C.G.

The scientists are still evaluating the vaccine’s long-term effects on Type 1 diabetes itself.

But they commissioned an independent group to look at Covid infections among the participants for 15 months, before any of them had received Covid vaccines.

The results were dramatic: only one — or slightly more than 1 percent — of the 96 people who had received the B.C.G.

People with Type 1 diabetes are particularly prone to infections.

in 300 older Greek adults, all of whom had health problems like heart or lung disease, found that the BCG vaccine reduced Covid-19 infections by two-thirds and lowered rates of other respiratory infections, as well.

Only two individuals who received the vaccine were hospitalized with Covid-19, compared with six who received the placebo shots, according to the study, published in July in Frontiers in Immunology.

“We have seen clear immunological effects of B.C.G., and it’s tempting to ask if we could use it — or other vaccines that induce training effects on immunity — against a new pathogen that emerges in the future, that is unknown and that we don’t have a vaccine for,” said Dr.

found no reduction in Covid infections, and a South African study of 1,000 health care workers found no impact of B.C.G.

The results of the largest trial of B.C.G., an international study that followed over 10,000 health care workers in Australia, the Netherlands, the U.K., Spain and Brazil for a year, are still being analyzed and are expected in the next few months.

The study also followed health care workers after they received Covid vaccines to see if B.C.G.

Type 1 diabetes patients in her study had received several B.C.G.