Washington DC, July 10: A century-old tuberculosis vaccine may play a role in reducing death due to Covid-19 infection, a preliminary study has suggested. Researchers from the US-based the National Institute of Allergy and Infectious Diseases of the National Institutes of Health made the link to Bacille Calmette-Guerin, or BCG, after comparing data on Covid-19 mortality rates across the globe.

In the study, published in online science journal 'Proceedings of the National Academy of Sciences of the United States of America', the researchers found that some Latin American regions - including Pernambuco, Rio de Janeiro and Sao Paulo in Brazil and Mexico City in Mexico - had considerably lower death rates than states in the US such as New York, Illinois, Louisiana and Florida. Bharat Biotech Vice-President Dr V.K. Srinivas Takes First Shot Of COVID-19 Vaccine? COVAXIN Developer Refutes Claim, Here's a Fact Check.

"This is remarkable, considering that [these parts of] Latin America have much higher population densities than the North American states analysed, including New York," wrote co-author Carolina Barillas-Mury.

In Europe, Germany also had surprising results - the death rate from Covid-19 was 2.9 times higher among people from the former West Germany than those in former East Germany. And the mortality rate was four times higher in Italy than in Finland.

According to the study, the places where death rates were lower varied in terms of age distribution, incomes, and health care access, but they all had one thing in common: a TB vaccination programme.

In Germany, for example, the BCG immunisation plans were different before the country was unified in 1990. The former East Germany began inoculating children against TB a decade earlier than in the West, meaning more older Germans in the eastern parts of the country were likely to have been given the vaccine. Older people are believed to be at increased risk from Covid-19.

Based on the data, the researchers estimated that a 10 per cent increase in TB vaccine coverage could lead to a 10 per cent reduction in deaths from Covid-19. As per South China Morning Post reports, the new study also challenged the World Health Organisation's position on the TB vaccine that "there is no evidence" it is effective - it is not the first study into the potential for BCG to protect against Covid-19.

BCG, named after French microbiologists Albert Calmette and Camille Guerin who developed it, contains a live strain of Mycobaterium bovis, which is related to the bacteria that causes TB.

The disease, which caused one in seven deaths in America and Europe at the turn of the 20th century, became preventable after the vaccine was introduced in 1921. Previous studies have found that the vaccine could also give children broad protection against other diseases such as respiratory infections not related to tuberculosis.