Why India’s social isolation approach on Covid-19 scores over UK’s ‘herd immunity’

Herd immunity stops the spread of an infectious disease by building mass immunity within a population, usually through vaccination.

The UK government’s highly unusual coronavirus disease (Covid-19) containment plan focuses on protecting vulnerable groups, but not complete elimination of the virus. The government wants young people to fall ill so they gain immunity against the virus.

Commuters walk past the Chhatrapati Shivaji Terminus railway station in Mumbai. (Bloomberg)

The Boris Johnson government has abandoned lockdowns, social isolation and other public health measures put in place elsewhere in Europe to contain Covid-19, going by the warped logic that young people will get a mild version of the disease and become immune to the virus, thus building “herd immunity” that would reduce transmission in the British population if the disease resurges in the winter.

Herd immunity stops the spread of an infectious disease by building mass immunity within a population, usually through vaccination. It is an established public health strategy that works by at least 95% of the population getting vaccinated, which not just protects the vaccinated people but also makes disease transmission difficult in the community as there are not too many unprotected people around to get infected.

The measles-rubella vaccine, for example, protects vaccinated people against the infection. If a person with measles was in a group of vaccinated people with antibodies against it, the disease would not get transmitted to anyone, which effectively ended transmission. This protected the entire ‘herd’ or community from infection, including those at a higher risk.

But no vaccine exists for Covid-19. It is a deadly pandemic that kills one in 25 people diagnosed with the disease. It’s a new virus and no one knows how it will behave over the next one year. And asymptomatic young people can infect vulnerable groups, raising the number of deaths.

“Herd immunity works during measles and chickenpox outbreaks, which are nowhere as contagious or deadly as Covid-19. Unlike Sars and Mers, Covid-19 is likely to be around for months, if not years. Abandoning action to rely on herd immunity to protect your population is utter fallacy, considering the number of people who risk dying,” said Dr Naresh Trehan, chairman, Medanta-The Medicity.

Sars is short for Severe Acute Respiratory Syndrome. Mers stands for the Middle East Respiratory Syndrome.

What works is social isolation that bring restrictions on study, work, travel and leisure. Restricting travel, closing schools, staggering work hours, working from home, teleconferencing and banning public gatherings, including for religious festivals, can lower risk of exposure and prevent infection.

“Restricting movement and self-quarantine are essential to stop the infection from spreading from person to person. This is why the government constantly updates travel advisories and social isolation strategies as the pandemic is evolving in India and the world,” said Dr Raman R Gangakhedkar, head, epidemiology and communicable diseases, Indian Council of Medical Research.