Is BCG vaccine giving us immunity we talk about?
Posted 02 Apr 2020 | Source: timesgroup.com
A study tracking the wide variation in the intensity of Covid-19 in different countries has suggested that the Bacillus Calmette-Guérin (BCG) vaccine used to prevent tuberculosis could be the reason for the slow progress of the disease in India. (Caveat: a lot more tests need to be carried out before drawing any conclusions). India has been vaccinating children with the BCG vaccine since 1949.
The study, by researchers at the biomedical sciences department, New York Institute of Technology’s College of Osteopathic Medicine found that Covid-19 cases and deaths are higher in countries that do not have or have discontinued universal BCG vaccination of children -- such as US, Italy, Spain and France -- compared to countries with universal and long-standing immunisation policies, such as India and Japan.
The study recommends BCG vaccination as a potential new tool in the fight against Covid-19. The study also answers why Covid-19 spread in China despite children getting BCG vaccinated since the 1950s. “During the Cultural Revolution (1966-1976), tuberculosis prevention and treatment agencies were disbanded and weakened. We speculate that this could have created a pool of potential hosts that would be affected by and spread Covid-19,” said the study.
City doctors speak
Dr Swati Rajagopal, Consultant - Infectious Disease & Travel Medicine, Aster CMI Hospital, said BCG is not a vaccine against Covid-19. “As per data, vaccines generally raise immune responses specific to a targeted pathogen, such as antibodies that bind and neutralize one type of virus but not others.
Dr Satyanarayana Mysore, HoD interventional pulmonology, Manipal Hospitals explains, “The immune system has two arms - Th1 and Th2. The Th1 is for fighting microorganisms and Th2 in general deals with auto-immunity. BCG boosts the Th1 arm. Other than TB, BCG is an immune booster used in leprosy, bladder cancer and colorectal cancer. The efficacy of BCG depends on a lot of factors. Hence, Western countries did not take up BCG vaccination.
“We do not know whether it is the BCG vaccination or the (prevalence of ) malaria that may be boosting our immune response to the Novel Corona outbreak. It is to be noted that the BCG vaccine may boost our immune system and that it does not do anything directly against Novell Corona. Controlled studies are needed to answer the question. Not wise to fall prey to the adage ‘desperate times, desperate remedies’,” he cautioned.
On the other hand Dr Jagadeesh Kumar P, Consultant Pulmonology, Apollo Hospitals Sheshadripuram, said: “Yes, this holds good in countries like India, Japan and Brazil. But if you see countries like Italy, US and Netherlands these countries have no universal BCG vaccination and the mortality rates in these countries are high. And in countries like India, Brazil and Japan they have Universal BCG vaccination and mortality rates are low. So BCG might grant long-lasting protection against this current strain of Covid-19 especially in the vaccinated geriatric population.”
However, there are many more sceptics within the medical community. Dr Siri Kamath, Consultant Physician at BGS Gleneagles Global Hospital Kengeri, cited the case of China where despite a universal BCG vaccination policy, the pandemic originated and infected over 81,000 people. “Covid-19 in India is still in early stages and it is difficult to predict what impact it is going to have on our population. There is similar speculation about malaria affected countries such as India and African countries being less affected by Covid-19,” he said.
Dr Vivekananda Padegal, director of Pulmonology, Fortis Hospital said, “BCG cannot be given now and made to fight against Covid-19. No one should start rushing to hospitals to get the vaccination.”
Social distancing (nay, physical distancing as discerning readers of Bangalore Mirror would say) and hand hygiene are the best methods to keep Covid-19 at bay, he said.
What other countries have done
Australia, Netherlands, Germany and the United Kingdom have already announced that they will begin large-scale human trials to see whether BCG vaccination protects health workers from Covid-19 by triggering an immune response to reduce symptoms, prevent severe illness or prevent infection.
Last Friday, Australia announced that it will begin BCG vaccine trials with around 4,000 physicians and nurses, who are at higher risk of becoming infected. Netherlands has recruited around 1,000 health care workers in eight Dutch hospitals to either receive the BCG vaccine or a placebo.