Herd immunity impractical health strategy: Study

New Delhi : Achieving herd immunity to COVID-19 is an impractical public strategy, say researchers, claiming that immunity is not perfect and achieving it through widespread exposure is very unlikely.

The study has been published in the journal Proceedings of the National Academy of Sciences; it analyses different kind of approaches which are being tested to take control over the spread of SARS-CoV-2, the virus that causes Covid-19.

"The herd immunity concept is tantalizing because it spells the end of the threat of Covid-19," said study lead author Toby Brett from University of Georgia in the US. 

"However, because this approach aims to avoid disease elimination, it would need a constant adjustment of lockdown measures to ensure enough people are being infected at a particular point in time," Brett added. 

The researchers tried to find a way with which countries could achieve herd immunity without putting an extra pressure on the healthcare system.

They developed an age-stratified disease transmission model to simulate SARS-CoV-2 transmission in the UK, with spread controlled by the self-isolation of symptomatic individuals and various levels of social distancing.

Their simulations found that in the absence of any control measures, the UK would experience as many as 4,10,000 deaths related to Covid-19, with 3,50,000 of those being from individuals aged 60-plus.

“If the virus spreads too quickly, hospitals will be overwhelmed, but if it spreads too slowly, the epidemic will be suppressed without achieving herd immunity,” the team wrote.

The team cautioned that if immunity is not perfect, and there is a significant chance of reinfection, achieving herd immunity through widespread exposure is very unlikely.

“We recognize there remains much for us to learn about Covid-19 transmission and immunity,” said study authors.