London, Sep 3 (IANS): The Bacille Calmette-Guerin or BCG vaccine, originally made against tuberculosis, gives an effective preventive action against various infections -- possibly also against Covid-19, say researchers, adding that it also protects elderly people from respiratory infections.

BCG is frequently given to children, but a double-blind randomised clinical study, published in the journal Cell, shows that elderly people also benefit from it.

"Two years ago we started the ACTIVATE study, with the aim of showing whether BCG vaccination could protect against infections in vulnerable elderly people," said study researcher Mihai Netea from Radboud University in the Netherlands.

According to the researchers, patients over 65 years of age who were admitted to hospital were randomised to receive BCG or placebo vaccination at their discharge.

"We followed them for a year to see if BCG could protect them against a broad range of infections," Netea said.

The team revealed that the ACTIVATE study had already started before the corona pandemic. A total of 198 elderly people were given either a placebo or a BCG vaccine upon discharge from the hospital.

During the research, there was a noticeable difference: in the placebo group, 42.3 per cent of the elderly developed an infection, while this was the case in only 25 per cent of the BCG group.

Also, the BCG-vaccinated participants had their first infection on average 16 weeks after vaccination, compared to 11 weeks for the placebo group. There was no difference in side effects.

"The most important observation was that BCG could mainly protect against respiratory infections: BCG-vaccinated elderly people had 75 per cent fewer respiratory infections than the elderly who received placebo," said study co-coordinator J. Giamarellos-Bourboulis.

Although most protection seems to have been against respiratory infections of (probably) viral origin, whether or not BCG also works against Covid-19 has not yet been demonstrated, due to the low prevalence of Covid-19 in this study, the team said.

However, the study does show that it is safe to give the BCG vaccination to the elderly and that it can protect them against various infections.

Several studies are underway that look specifically at the effects of BCG on Covid-19.

Last month, a study published in the journal 'Cell Reports Medicine', revealed that the BCG vaccine has a general stimulating effect on the immune system and is, therefore, effective against Covid-19.