Coronavirus death rates are nearly six times lower in countries that use a nearly century-old tuberculosis vaccine, a new study found.
The study, conducted by researchers at the Johns Hopkins Bloomberg School of Public Health, found that the COVID-19 mortality rate among countries that use the Bacillus Calmette-Guérin (BCG) vaccination was 5.8 times lower than in those that do not.
“Demonstration that exposure to BCG vaccination can ameliorate severe COVID-19 disease and lower mortality could rationalize a therapeutic or preventive strategy that can have immediately deployable global impact,” the researchers wrote.
“Therefore, using existing publicly available data, we examined at the ecological level whether country-level COVID-19 mortality was associated with BCG use in national immunization schedules.”
The vaccine, first administered to a human in 1921 and primarily used to protect against tuberculosis, is undergoing clinical trials to test its ability to ward off COVID-19.
Using the mortality per one million residents of each country with sufficient data, researchers estimated the coronavirus fatality rate from the 50 countries with the highest number of cases.
After accounting for the economic status of the countries and their elderly populations — both of which contribute to death rates — “the intriguing observation of a significant association between BCG use and lower COVID-19-attributable mortality remained discernable,” the researchers said.
The researchers said that the findings “warrant deeper epidemiological scrutiny and prospective evaluation in individually randomized trials.”
The World Health Organization said this week that there is currently “no evidence” that the BCG vaccine can protect people from the coronavirus, but two clinical trials are underway.
The WHO will “evaluate the evidence when it is available,” and does not currently recommend the vaccination for the prevention of COVID-19, it said.
Studies like the Johns Hopkins one, which has yet to be peer-reviewed, “are prone to significant bias from many confounders, including differences in national demographics and disease burden, testing rates for COVID-19 virus infections, and the stage of the pandemic in each country,” the organization said.
Researchers at the Murdoch Children’s Research Institute in Melbourne, Australia are probing whether the vaccine could protect health care workers on the front line from the deadly bug.
“I think BCG vaccine is a bit of the equivalent of a Hail Mary pass,” Dr. William Schaffner, an infectious disease specialist at the Vanderbilt University School of Medicine, told WBZ-TV this week. “It’s such an outside-the-box concept that one would like to be optimistic, but we’ll have to wait and see.”