Why a Century-Old Vaccine Offers New Hope Against Pathogens
The B.C.G. 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.
Scientists observed many years ago that the vaccine seems to train the immune system to respond to a variety of infectious diseases, including viruses, bacteria and parasites, and reduces infant mortality.
ADVERTISEMENT
As new threats like monkeypox and polio re-emerge and the coronavirus continues to evolve, the potential of the old vaccine to provide a measure of universal protection against infectious diseases has gained renewed interest among scientists.
Now the results of clinical trials conducted during the pandemic are coming in, and the findings, while mixed, are encouraging.
The latest results, published Monday in Cell Medicine Reports, come from a trial initiated before Covid-19 emerged. It was designed to see whether multiple B.C.G. injections could benefit people with Type 1 diabetes, who are highly susceptible to infection.
In January 2020, as the pandemic began, the 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 received multiple placebo injections.
ADVERTISEMENT
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. doses developed Covid, compared with six — or 12.5 percent — of the 48 participants who received dummy shots.
Although the trial was relatively small, “the results are as dramatic as for the Moderna and Pfizer mRNA vaccines,” said Dr. Denise Faustman, the study’s lead author and director of immunobiology at Massachusetts General Hospital.
Read More on the Coronavirus Pandemic
- Boosters: Britain became the first country to authorize a coronavirus vaccine that targets two variants. Half of each dose of the Moderna-made shot will target the original variant, and the other half will target Omicron.
- New Guidelines: The Centers for Disease Control and Prevention loosened its Covid-19 guidance, saying those exposed to the virus no longer need to quarantine. A day later, the U.S. Food and Drug Administration recommended that people exposed to Covid who are asymptomatic take at least three at-home antigen tests, each spaced 48 hours apart, to reduce the risk of missing an infection.
- A Century-Old Vaccine: The results of clinical trials, launched in the early days of the pandemic, involving an old tuberculosis vaccine offered hope that it could provide a measure of universal protection against infectious diseases.
People with Type 1 diabetes are particularly prone to infections. “We saw a major decrease in bladder infections, less flu and fewer colds, less respiratory tract infections and less sinus infections that diabetics get a lot of,” Dr. Faustman added.
ADVERTISEMENT
The vaccine “seems to be resetting the immune response of the host to be more alert, to be more primed, not as sluggish.”
Another trial of B.C.G. in 300 older Greek adults, all of whom had health problems like heart or lung disease, found that the BCG vaccine reduced Covid-19 infectionsby 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.
An earlier version of this article incorrectly described the composition of the B.C.G. vaccine. It contains a weakened version of a bacterium, not a virus.
An earlier version of this article incorrectly described the percentage represented by the 1 in 96 people who received B.C.G. tuberculosis vaccine doses and developed Covid. It is slightly more, not less, than 1 percent.
No comments:
Post a Comment