COVID-19: Herd immunity is not possible without collateral damage

Herd immunity can break the chain of transmission and stop COVID-19 in its track. But can this be achieved without suffering any collateral damage like a major hike in mortality rates?

By: Jahnavi Sarma | | Updated: July 9, 2020 8:53 am

Experts say that instead of aiming for herd immunity, slowing down the transmission makes more sense.

In the absence of a vaccine for COVID-19, many scientists strongly suggest developing herd immunity. According to them, this can be a potential weapon that may stop the viral infection in its track. This can happen when a huge percentage of the population is exposed to the virus. When they get infected, they will develop immunity against it. Experts say that this will break the chain of transmission and significantly bring down cases of new infection. India, which has a relatively higher young population may benefit from this strategy, they say. But can this be achieved without suffering any collateral damage like a major hike in mortality rates? Also Read - Can alternative therapies help us in our battle against the COVID-19 pandemic?

A new study in Spain does not seem to think so. Researchers there have found that only five per cent of the population in Spain has developed antibodies, nowhere near the levels needed to achieve ‘herd immunity’. Herd immunity is achieved when enough people become infected with a virus to stop its spread. Also Read - COVID-19 Live Updates: Cases in India surge to 22,68,675 as death toll reaches 45,257

90 per cent population needs to be immune to protect uninfected

This nationwide population-based study aims to estimate the seroprevalence of SARS-CoV-2 (coronavirus) infection in Spain at the national and regional level. For the findings, the research team picked more than 60,000 participants. They answered a questionnaire on a history of symptoms compatible with COVID19 and risk factors. The study provides nationwide and regional estimates of COVID-19 dissemination in Spain, showing remarkable differences between higher and lower prevalence areas. Also Read - COVID-19 and Immunity: Fermented foods to boost your defence mechanism

The findings showed that one in three infections seems to be asymptomatic, while a substantial number of symptomatic cases remained untested. Data from participants – who ranged in age from infants to people in their 90s – showed some variation by region but nowhere near levels needed for herd immunity. The prevalence of COVID-19 antibodies was less than three per cent in coastal regions, but more than five times higher in areas with major outbreaks. According to a nationwide study, published in the journal The Lancet, to achieve herd immunity that would protect the uninfected, around 70 per cent to 90 per cent of a population needs to be immune to protect the uninfected.

Herd immunity not possible without collateral damage

According to the study, despite the high impact of COVID-19 in Spain, prevalence estimates remain low and are clearly insufficient to provide herd immunity. This cannot be achieved without accepting the collateral damage of many deaths in the susceptible population and overburdening of health systems. In this situation, social distance measures and efforts to identify and isolate new cases and their contacts are imperative for future epidemic control.

Working towards herd immunity may not be a good idea

Currently there is no vaccine for COVID-19. Mass exposure to the virus in a country like India can lead to a catastrophic death toll. Since the mortality rate in India is around 5 per cent at present, 5 out of 100 infected patients may die. And, this is a conservative estimate. In a highly populated country like India, is it really feasible to push so many people to death’s door? Moreover, this virus mutates very fast. So, antibodies will offer protection only for a few months at the most. So, the heavy cost in terms of human life does not really make sense. Experts say that instead of aiming for herd immunity, slowing down the transmission makes more sense. For this, it becomes very necessary to follow the precautionary measures like social distancing and wearing face masks diligently.

(With inputs from IANS)

Published : July 8, 2020 10:34 am | Updated:July 9, 2020 8:53 am

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