Vaccinations against Tuberculosis administered in the last 15 years may provide additional protection against COVID-19 to people under 24 years of age, according to a new study published recently in Vaccines.

Dr. Nadav Rappoport of BGU’s Department of Software and Information Systems Engineering? collaborated with colleagues from The Hebrew University of Jerusalem to analyze the correlation between countries’ policies for the Bacille Calmette-Guérin (BCG) vaccine for tuberculosis and countries’ COVID-19 outcomes.

They discovered that BCG regimes are associated with some protection from COVID-19, either reducing infection rates or reducing death rates. The protection was significant among those 24 years old and younger who had received the vaccination in the last 15 years. There was no effect among older adults who had received the BCG vaccine years ago.

The BCG vaccine is still widely administered, however, some countries have stopped inoculating their entire populations with it.

Rappoport and his colleagues analyzed normalized data from 55 countries around the world, which comprise 62.9% of the world’s population. To normalize the data, they included countries with populations more than 3 million. As the pandemic reached different countries at different dates, they aligned countries by the first date at which the country reached a death rate of 0.5 deaths per million or higher. They controlled for demographic, economic, pandemic-restriction-related and health-related country-based variables.

Their data revealed the BCG vaccine was consistently in the top 2 effects across the 55 countries.

To ascertain whether other vaccines also influenced COVID-19 outcomes, they conducted the same analysis for the measles and rubella vaccines. They found that those vaccines did not have a significant association with COVID-19 outcomes.

Other epidemiological studies have shown the effect of the BCG vaccine beyond tuberculosis, but scientists do not yet know why the vaccine has such an effect.

“Our findings suggest exploring BCG vaccine protocols in the context of the current pandemic could be worthwhile,” says Rappoport.