TB vax linked to lower risk of contracting Covid-19

New York: New research adds to a growing body of evidence that Bacillus Calmette-Guerin (BCG), a vaccine for tuberculosis (TB), is associated to reduced possibility of contracting the Covid-19 virus.

In the new study, published in The Journal of Clinical Investigation, the research team tested the blood of more than 6,000 healthcare workers for evidence of antibodies to SARS-CoV-2, the virus that causes Covid-19, and also asked them about their medical and vaccination histories.

They found that workers who had received BCG vaccinations in the past-nearly 30 per cent of those studied-were significantly less likely to test positive for SARS-CoV-2 antibodies in their blood or to report having had infections with coronavirus or associated symptoms over the prior six months than those who had not received BCG.

These effects were not related to whether workers had received meningococcal, pneumococcal or influenza vaccinations.

The reasons for the lower SARS-CoV-2 antibody levels in the BCG group were not clear, according to the researchers.

"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 study author Moshe Arditi, Cedars-Sinai Medical Centre in the US.

"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," Arditi added.

In the study, the lower antibody levels in the BCG group persisted despite the fact that these individuals had higher frequencies of hypertension, diabetes, cardiovascular diseases and COPD.

"Given our findings, we believe that large, randomized clinical trials are urgently needed to confirm whether BCG vaccination can induce a protective effect against SARS-CoV2 infection," said study author Susan Cheng from Cedars-Sinai.

Earlier in October, as part of a large-scale global trial, scientists in Britain had launched a study to test if the widely-used Bacillus Calmette-Guerin (BCG) vaccine could help protect people against Covid-19.

Also, a study appeared in the pre-print repository medRxiv, found that TB vaccine could be a potential new tool in the fight against the Covid-19 disease.