Science

‘Herd immunity’ not a strategy in an outbreak, let alone a pandemic: WHO Chief

PT Jyothi Datta Mumbai | Updated on October 13, 2020 Published on October 13, 2020

Director General of the World Health Organization, Tedros Adhanom Ghebreyesus (file photo)   -  Reuters

Mentions use of targeted digital tools, including India’s Aarogya Setu app, among others

The World Health Organization has shot down the concept of achieving “herd immunity” by letting the novel coronavirus (SARS-COV2) spread.

“Never in the history of public health has herd immunity been used as a strategy for responding to an outbreak, let alone a pandemic. It is scientifically and ethically problematic,” said WHO Director General, Dr Tedros Adhanom Ghebreyesus.

Herd immunity is a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached, he said. For example, herd immunity against measles requires about 95 per cent of a population to be vaccinated. The remaining 5 per cent will be protected by the fact that measles will not spread among those who are vaccinated. For polio, the threshold is about 80 per cent, he added.

“In other words, herd immunity is achieved by protecting people from a virus, not by exposing them to it,” he said.

Besides, the world does not know enough about immunity to the virus, he said, even as reports emerge from across the world on reinfection. And there’s also the long-term impact from the infection, or “long Covid”, he said.

“Most people who are infected with the virus that causes Covid-19 develop an immune response within the first few weeks, but we don’t know how strong or lasting that immune response is, or how it differs for different people. We have some clues, but we don’t have the complete picture,” he said.

Hope to finish the Covid-19 pandemic in less than two years: WHO Chief

A vast majority of people in most countries remain susceptible to this virus, he said, adding that that seroprevalence surveys suggest that less than 10 per cent of the population has been infected with the virus.

“Letting the virus circulate unchecked therefore means allowing unnecessary infections, suffering and death,” he said. And increasingly, people of all ages are getting affected and dying, he said.

“Allowing a dangerous virus that we don’t fully understand to run free is simply unethical. It’s not an option,” he said.

Digital tools

But the options countries do have to tackle the situation included targeted measures, including apps, he said, mentioning India’s Aarogya Setu, among others.

This virus transmits mainly between close contacts and causes outbreaks that can be controlled by implementing targeted measures. “Prevent amplifying events. Protect the vulnerable. Empower, educate and engage communities,” he said.

Digital technologies are helping to make these tried-and-tested public health tools even more effective, such as mobile applications to support contact tracing efforts.

Germany’s Corona-Warn app has been used to transmit 1.2 million test results from labs to users in its first 100 days. The Aarogya Setu app from India has been downloaded by 150 million users, and has helped city public health departments to identify areas where clusters could be anticipated and expand testing in a targeted way.

And in Denmark, more than 2,700 people have been tested for Covid-19 as a result of notifications received through a mobile application. The UK too has rolled out a new version of its NHS COVID-19 app, which had more than 10 million downloads within the first week. As well as alerting users that they may have been exposed to a positive Covid-19 case, the app allows users to book a test and receive results, keep track of the places they’ve visited and receive the latest advice on local restrictions, he said.

In fact, the WHO is working with the European Centre for Disease Prevention and Control to help countries evaluate the effectiveness of their digital contact-tracing apps, he added.

“We well understand the frustration that many people, communities and governments are feeling as the pandemic drags on, and as cases rise again,” he said, adding there were no short cuts, and no silver bullets.

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Published on October 13, 2020
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