The ICMR will conduct a study to find the efficacy of BCG vaccine against COVID-19 and till any definitive result is reached it will not recommended the vaccine even for healthcare workers, officials said on Friday.

Bacillus Calmette-Guerin (BCG) is a vaccine primarily used against tuberculosis.

Head of Epidemiology and Communicable diseases at the Indian Council of Medical Research (ICMR) Dr Raman R Gangakhedkar said the apex health research body will begin a study on the effectiveness of the vaccine against coronavirus infection next week.

"Till the results of the study are out and evidence is obtained, we will not recommend the vaccine even to health workers," he said in response to a question regarding its usage at a press briefing on Friday.

Elaborating on the usage of the vaccine, Dr Gangakhedkar said it is administered immediately after birth. The BCG vaccine cannot even prevent one from the risk of contracting TB but provides partial protection from tuberculous meningitis, he said.

BCG's benefit, according to some studies, is in some malignant cancer cases where it may improve the resistance power by working as an immunomodulator on the body to kill the target cells.

"However, in COVID-19, the chances are less because BCG vaccine gives protection for a maximum of 15 years. Studies suggest that if re-vaccination has to be done, then it should be done in adolescence.

"What that effectively means is that if one is 70 years old and COVID-19 positive, then one cannot be protected by BCG vaccine," Dr Gangakhedkar said, adding there is not enough evidence to state that getting a repeat BCG vaccination will protect someone who is above 15 years against coronavirus infection.

He was also asked about researchers at the Gujarat government-run Biotechnology Research Centre claiming success in decoding the entire genome sequence of the novel coronavirus and in identifying its three new mutations. They have expressed confidence that the findings will help in developing medicines or vaccines.

To this, Dr Gangakhedkar said decoding the whole genome sequence of the virus has not been done for the first time.

"People from different countries bring various virus species while travelling. We have seen presence of various species of the virus in our country," he said.

Three novel coronavirus strains have been traced in India -- the first one was from China's Wuhan and the other two from Italy and Iran. Although, the genome sequence of the novel coronavirus strain from Iran was similar to that from China.

"It will take some time for us to know the predominant quasi-species of novel coronavirus in the country. But mutations are not likely to make potential vaccines ineffective, as all sub-types of the virus have same enzymes. Also it has been in India for three months and it does not mutate very fast," Dr Gangakhedkar said. "Whatever vaccine comes out, we can say as of now that it may work in the future if the virus mutates," he said.