Coronavirus pandemic

Coronavirus: Why Singapore has not adopted herd immunity strategy to fight virus

The Ministry of Health's director of medical services Kenneth Mak said that reaching herd immunity to Covid-19 through natural infection in the population would lead to many deaths and infections and overwhelm the healthcare system, adding that it wo
The Ministry of Health's director of medical services Kenneth Mak said that reaching herd immunity to Covid-19 through natural infection in the population would lead to many deaths and infections and overwhelm the healthcare system, adding that it would be "too big a price for us to pay". ST PHOTO: GIN TAY

Achieving herd immunity to Covid-19 through natural infection in the population will lead to a higher number of deaths and infections and overwhelm Singapore's healthcare system, said the Health Ministry's (MOH) director of medical services Kenneth Mak.

Speaking during a virtual briefing yesterday, Associate Professor Mak made clear that there was "too big a price for us to pay" to reach herd immunity in this way and thus it has not been part of Singapore's strategy to fight the coronavirus pandemic.

"If we assume that we're going to let Covid-19 spread freely in our population, we will then have to accept the costs associated with more seniors getting ill, more seniors getting complications, and a significant number of seniors even dying from infection.

"We will then see also high numbers of patients with Covid-19 infection potentially in our hospitals, in our ICUs, and this is a situation which is a very dangerous one."

He added that if the virus is contained well in Singapore, the country will never reach a situation where herd immunity is achieved, unless vaccination takes place.

Experts estimate that about 60 per cent to 80 per cent of the population needs to be infected and immune to the virus before herd immunity can be achieved, although such figures are often "best guesses", said Associate Professor Vernon Lee, director of communicable diseases at MOH.

Prof Lee, who also spoke yesterday, noted that countries which had high numbers of infections and conducted serological testing - which detects antibodies to determine whether a person has been infected - found that the percentage of positives was "way below" the threshold needed for herd immunity.

"So to get to that kind of percentage to achieve herd immunity will require a large number of people to get infected... So far, I don't think there's any country in the world that has tried to use overall herd immunity as a strategy to combat Covid-19," he said.

Yesterday, MOH confirmed 884 new coronavirus cases in Singapore, taking the country's total number of infections past 24,000.

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The concept of herd immunity, where the virus spreads in the population, eventually building up resistance in the population, was initially key to the British government's decision-making when battling Covid-19, reported British newspaper The Guardian. However, the government abandoned this idea when it realised this would cause the healthcare system to be overwhelmed and potentially lead to the deaths of hundreds of thousands of people.

Sweden, which has been criticised for its soft lockdown measures, has reported more than 3,200 deaths from the disease - several times higher than the number of deaths in neighbouring Scandinavian countries. The Swedish authorities have denied that their strategy was based on the overall goal of herd immunity.

Toh Wen Li

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A version of this article appeared in the print edition of The Straits Times on May 13, 2020, with the headline Coronavirus: Why Singapore has not adopted herd immunity strategy to fight virus. Subscribe