New study finds a correlation, but clinical trials are still in progress
Countries with mandatory policies to vaccinate against tuberculosis register fewer coronavirus deaths than countries that don’t have those policies, a new study has found.
The preliminary study posted on medRxiv, a site for unpublished medical research, finds a correlation between countries that require citizens to get the bacillus Calmette-Guerin (BCG) vaccine and those showing fewer number of confirmed cases and deaths from Covid-19. Though only a correlation, clinicians in at least six countries are running trials that involve giving frontline health workers and elderly people the BCG vaccine to see whether it can indeed provide some level of protection against the new coronavirus.
Gonzalo Otazu, assistant professor at the New York Institute of Technology and lead author of the study, started working on the analysis after noticing the low number of cases in Japan. The country had reported some of the earliest confirmed cases of coronavirus outside of China and it hadn’t instituted lockdown measures like so many other countries have done.
Among high-income countries showing large number of Covid-19 cases, the U.S. and Italy recommend BCG vaccines but only for people who might be at risk, whereas Germany, Spain, France and the U.K. used to have BCG vaccine policies but ended them years to decades ago. China, where the pandemic began, has a BCG vaccine policy but it wasn’t adhered to very well before 1976, Otazu said. Countries including Japan and South Korea, which have managed to control the disease, have universal BCG vaccine policies. Data on confirmed cases from low-income countries was considered not reliable enough to make a strong judgment.
“I would read the results of the study with incredible caution,” Fish said.
Otazu, who said he’s already received comments from other experts, is working on a second version of his study that will address some of their concerns. He has also submitted the study for a formal review process with the journal Frontiers in Public Health.
One of the first to conduct the trial of BCG vaccine’s effectiveness against coronavirus is Mihai Netea, an infectious-disease expert at Radboud Universty Medical Center in the Netherlands. Netea’s team has already enrolled 400 health workers in the trial”-200 got the BCG vaccine and 200 received a placebo. He doesn’t expect to see any results for at least two months. He’s also about to start a separate trial to study the effectiveness of the BCG vaccine on those older than 60. Other trials are taking place in Australia, Denmark, Germany, the U.K. and the U.S.
“It’s like the BCG vaccine creates bookmarks for the immune system to use later in life,” Netea said.
Even if BCG vaccine is shown to be effective, that’s no reason to stockpile.
“People should not hoard or try to get BCG vaccine like they did toilet paper,” Otazu said. There is a small chance that the BCG vaccine could increase the risk of coronavirus, but scientists won’t know until after the clinical trials.
In any case, the BCG vaccine shouldn’t be the only tool to fight Covid-19.