The hypothesis that the BCG vaccine might help mitigate the effects of SARS-CoV-2 that had already been suggested by previous studies is now supported by additional evidence in a recent study by a team of virologists at Cedars-Sinai Medical Center.
Bacillus Calmette-Guérin (BCG)
The old Bacillus Calmette-Guérin (BCG) vaccine is given to more than 100 million children worldwide each year. This anti-tuberculosis vaccine that is given mostly in underdeveloped countries confirms its ability to protect against COVID-19 disease in a paper presented in the Journal of Clinical Investigation.
BCG has already been approved by health authorities around the world, including the FDA and the WHO, and appears to be an affordable and accessible option to help prevent coronavirus infections or reduce the severity of the disease. The BCG vaccine is currently being tested for its effectiveness against COVID-19 in several clinical trials around the world.
BCG vaccination appears to “slow down” COVID-19 disease
Here, researchers analyzed blood samples from over 6,000 health care workers in the Cedars-Sinai health care network for anti-SARS-CoV-2 antibodies and also asked these participants about their medical and vaccination history. The analysis showed that:
- Healthcare workers who had been vaccinated with the BCG vaccine – about 30% of the participants – were less likely to test positive for anti-SARS-CoV-2 antibodies.
- They were also less likely to have had coronavirus coronavirus-related infections or symptoms in the previous 6 months.
- These results are not found with other vaccines (meningococcal, pneumococcal, or influenza).
- Finally, the lower antibody levels in the BCG group were found even in the presence of hypertension, diabetes, cardiovascular disease, and COPD, which are factors of vulnerability to SARS-CoV-2.
Why lower antibodies in those vaccinated with the BCG vaccine?
The reasons for the lower levels of anti-SARS-CoV-2 antibodies in the BCG-vaccinated group of participants are not so simple: lead author Dr. Moshe Arditi, director of the Department of Pediatric Infectious Diseases and Immunology at Cedars-Sinai suggests that “people vaccinated with BCG were less sick and therefore produced fewer anti-SARS-CoV-2 antibodies, or perhaps developed a more effective cellular immune response against the virus.”
Large randomized clinical trials are currently underway to confirm whether BCG vaccination can induce a protective effect against SARS-CoV2 infection.
The authors do not claim that BCG will be more effective than any specific COVID-19 vaccine, but the BCG vaccine could be approved for this indication more quickly than let’s say a new vaccine. Also having it in the arsenal against COVID could help during the transitional period until enough COVID-19 vaccine doses become available especially where supplies of currently approved vaccines are not available in sufficient quantities. Furthermore, the BCG vaccine could be given to first-line responders for extra protection especially with the new variants of SARS-CoV-2 that keep appearing all the time.