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BCG Vaccine Shows More Promise Against COVID-19 in Medical System Study

Cedars-Sinai healthcare workers who received a common tuberculosis vaccine at some point in their lives were significantly less likely to test positive for SARS-CoV-2 antibodies or to report having had infections with coronavirus or coronavirus-associated symptoms over the prior six months than those who had not received the vaccine. Furthermore, co-morbidities didn’t seem to matter. Here are more details.

LOS ANGELES – Testing of more than 6,000 healthcare workers at Cedars-Sinai Health System has bolstered evidence that a widely used tuberculosis vaccine might reduce the risk of contracting COVID-19 or having a serious case.

Authors of the study published in the Journal of Clinical Investigation say the research heightens the possibility that a vaccine already approved by the U.S. Food and Drug Administration could be beneficial in combating the pandemic.

The Bacillus Calmette-Guérin (BCG) vaccine is about 100 years old and is administered to more than 100 million children around the world every year. In the United States, it is FDA-approved to treat bladder cancer and as a vaccine for those at high risk of contracting TB.

The current study involved the testing of Cedars-Sinai healthcare workers for evidence of antibodies to SARS-CoV-2, the virus that causes COVID-19. The study team also asked them about their medical and vaccination histories. Evidence of having received the BCG vaccine was documented for about 30% of them.

Results indicate that workers who had received BCG vaccinations in the past were significantly less likely to test positive for SARS-CoV-2 antibodies or to report having had infections with coronavirus or coronavirus-associated symptoms over the prior six months than those who had not received BCG. Yet, researchers point out, those effects appeared not to be related to whether workers had received meningococcal, pneumococcal or influenza vaccinations.

Of the 6,201 healthcare workers (HCW) tested, 29.6% reported a history of BCG vaccination, researchers note, adding, “After adjusting for age and sex, we found that history of BCG vaccination, but not meningococcal, pneumococcal or influenza

The study adds, “Therefore, large randomized prospective clinical trials of BCG vaccination are urgently needed to confirm if BCG vaccination can induce a protective effect against SARS-CoV2 infection.”

A possible reason for the benefit, according to the authors, is that the BCG demonstrates non-specific protective innate immune-boosting effects.

"It appears that BCG-vaccinated individuals either may have been less sick and therefore produced fewer anti-SARS-CoV-2 antibodies, or they may have mounted a more efficient cellular immune response against the virus," said co-senior author Moshe Ardti, MD,, director of the Pediatric and Infectious Diseases and Immunology Division at Cedars-Sinai, “We were interested in studying the BCG vaccine because it has long been known to have a general protective effect against a range of bacterial and viral diseases other than TB, including neonatal sepsis and respiratory infections."

One notable finding, according to the study, is that the lower antibody levels in the BCG group occurred even though those workers tended to have likelihood of hypertension, diabetes, cardiovascular diseases and COPD, which are known risk factors for being more susceptible to SARS-CoV-2 and developing the more severe forms of COVID-19 illness.

Demonstrating effectiveness of the BCG vaccine against COVID-19 is “a potentially important bridge that could offer some benefit until we have the most effective and safe COVID19 vaccines made widely available," Ardti said.