A tuberculosis vaccine may help reduce the risk of death from Covid-19, researchers suggest.
Developing countries have lower-than-expected Covid-19 death rates, and a TB vaccine given in countries with high rates of tuberculosis might play a significant role in reducing Covid-19 death rates, according to authors of a new study.
The vaccine, which is routinely given to children in countries where TB infection is common, is called Bacille Calmette-Guérin, or BCG for short. It is not widely used in the United States.
"In our initial research, we found that countries with high rates of BCG vaccinations had lower rates of mortality," said Luis Escobar, an assistant professor in the College of Natural Resources and Environment at Virginia Tech.
"But all countries are different: Guatemala has a younger population than, say, Italy, so we had to make adjustments to the data to accommodate those differences," he said in a university news release.
For the study, Escobar and colleagues at the US National Institutes of Health collected Covid-19 death data from around the world.
They adjusted for variables such as income, access to education and health services, population and age distribution. Through all of the variables, there was a persistent link between higher rates of BCG vaccination and lower peak Covid-19 death rates.
"The purpose of using the BCG vaccine to protect from severe Covid-19 would be to stimulate a broad, innate, rapid-response immunity," Escobar said.
BCG vaccines have been shown to provide broad protection for several viral respiratory illnesses in addition to tuberculosis, he noted.
The findings are preliminary and did not prove cause and effect. More research is needed, Escobar stressed.
"We're not looking to advise policy with this paper," Escobar said. "This is, instead, a call for more research. We need to see if we can replicate this in experiments and, potentially, in clinical trials. We also need to come back to the data as we get more information, so we can reevaluate our understanding of the coronavirus pandemic."
The World Health Organization said there is no current evidence that the BCG vaccine can protect against Covid-19, and it is not recommended for that purpose.
Clinical trials are underway to determine whether BCG vaccination in adults provides protection from severe Covid-19.
The study was published July 9 in the journal Proceedings of the National Academy of Sciences.
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