A country-wide serosurvey conducted by the Council of Scientific and Industrial Research has found that smokers, vegetarians and those with blood group 'O' may be less susceptible to contracting the COVID-19 infection, indicated by the lesser seropositivity found among these groups.

The survey, published in a premedical journal and yet to be peer-reviewed, looked at 10,427 individuals working in CSIR laboratories as well as their family members to detect the presence of antibodies in them, PTI reported.

Findings

Over 1,000 individuals were found to have antibodies against the novel coronavirus - constituting 10.14 percent of the total. A follow-up after three months of 346 of them showed that the antibody levels were ‘stable’ or ‘higher’ but the plasma activity for neutralizing the virus had decreased, said Shantanu Sengupta, senior scientist at CSIR-Institute of Genomics and Integrative Biology (IGIB) and a co-author, quoted PTI.

"The aggregate seropositivity of 10·14% suggested that more than a hundred million Indians were infected by September 2020, primarily in larger cities but rapidly spreading all over the nation,” the study said.

“Our finding that smokers are less likely to be seropositive is the first report from the general population and part of growing evidence that despite COVID-19 being a respiratory disease, smoking may be protective," the study said.

As part of the growing evidence, the study cites papers from France, Italy, New York and China where a similar trend has been observed.

“The presence of such antibodies is a reliable marker of infection and recovery. However, some infected people may not develop antibodies," Anurag Agrawal, IGIB director, and one of the co-authors of the paper said.

Earlier last year, medical practitioners, as well as the government, had warned about smokers likely to be susceptible to more severe disease considering COVID is a largely respiratory infection.

Top bodies, WHO and CDC too had warned smokers. World Health Organisation, while answering if smokers and tobacco users are at a higher risk of COVID-19, had said,

“Smokers are likely to be more vulnerable to COVID-19 as the act of smoking means that fingers (and possibly contaminated cigarettes) are in contact with lips which increases the possibility of transmission of virus from hand to mouth. Smokers may also already have lung disease or reduced lung capacity which would greatly increase the risk of serious illness”.

(With inputs from PTI)