Science

Covid-19: India moving towards 'undeclared herd immunity'

Vinson Kurian Thiruvananthapuram | Updated on August 03, 2020 Published on August 03, 2020

A leading molecular immunologist has said that, in the absence of a vaccine, herd immunity against Covid-19 can be controlled only by limiting the spread of disease. It is an ongoing process and is achieved commensurate with the rate of the disease spread, says Germany-based Dr Satish Ranjan.

Herd immunity against the pandemic is a gradual biological process achieved when 60-70 per cent of the population gets infected by the Covid-19 virus and develops antibodies. It’s not as if people may wait for a vaccine to get immunised and in turn attain herd immunity, he said in an Email to BusinessLine.

'No strategic option'

He said this in response to a statement reportedly made by Rajesh Bhushan, a top official of the Union Ministry of Health and Family Welfare in New Delhi on July 31. He had said that herd immunity in a country of the size and population of India can’t be a strategic option and that it can only be achieved through immunisation.

This would have made sense if the government had been able to check the spread of disease, Dr Ranjan said. But this is far from reality when the disease is spreading with every passing day. With more and more people getting infected, India is moving towards ‘undeclared herd immunity,’ Dr Ranjan said.

Happening in reality

The Centre may not have announced herd immunity as a strategic option, but it is happening in reality. To support his case, Dr Ranjan referred to the outcome of Delhi’s sero-prevalence study. It had revealed that 23.48 per cent of Delhi’s population has been exposed to the Coronavirus and has developed antibodies.

If this finding is correct, it means in real terms that millions of people have been infected so far, which is way above the actual diagnosed numbers. If these many are already infected despite all control measures including lockdown, then Delhi is moving closer to ‘undeclared herd immunity.’ If the same trend were to continue, Delhi might go on to attain herd immunity soon, Dr Ranjan said.

Past the post in Mumbai?

The spread of Covid-19 in the slum areas of Mumbai where 57 per cent dwellers have already been infected suggests that it has almost achieved herd immunity naturally by getting exposed to the virus rather than by immunisation through a vaccine, Dr Ranjan said.

Vaccines are outcomes of rigorous scientific work that is in turn supported by experimental data and is most of the time peer-reviewed, authenticated and validated. Dr Ranjan requested the Union Ministry to present data about the vaccine being readied for India and dwell on the specifics of its stage of development.

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Published on August 03, 2020
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