Coronavirus: Sweden's herd immunity policy could cost 60,000 lives - professor

Sweden's attempt to achieve herd immunity to COVID-19 is a "fatal mistake" and could cost them up to 60,000 lives, a health expert claims.

Writing for NZME, Professor of epidemiology at the University of Auckland Rod Jackson says about 60 in every 100 people need to either be infected or vaccinated to reach herd immunity against the virus.

Furthermore, a lot of evidence suggests the average Infection Fatality Proportion (IFP) is about one death per 100 infections for the disease. The IFP helps to estimate how many deaths there could be and how close a population is to reaching herd immunity.

But for Sweden to achieve herd immunity, it must believe the IFP is closer to one death per 1000 infections, Jackson says.

Over 4200 people have died in Sweden from the virus so far and it has a population of 10 million. This makes the death rate under its reasoning about 400 deaths per one million people.

If the IFP was one death per 1000 infections, he says about 40 of every 100 people there would've been infected and it would be close to herd immunity. It could also only expect 2000 more deaths to reach this.

But if the current best-estimate IFP actually is about one death per 100 infections, then that means only four in 100 people have already been infected.

"This would mean that at the current rate of infection, it would take more than two years for Sweden to reach herd immunity and an additional 56,000 lives could be lost in the process, unless a vaccine or effective treatments are developed," Jackson says.

He reached the number of 56,000 by showing if 60 out of 100 people need to be infected to reach herd immunity, then six million of the 10 million population will need to be infected. And if the IFP is one death for every 100 infections, then one in every 100 of these six million people will die: hence 60,000. Since 4000 people have already died, it means another 56,000 could still die to reach this figure.

Jackson says a new study shows only 7.3 people in every 100 in Stockholm have antibodies to COVID-19, despite the rest of the country having a higher death rate.

"This is unfortunately consistent with the worst-case scenario estimates presented here. The conclusion should now read: 'Sweden has made a fatal mistake'."

Sweden's former chief epidemiologist Johan Giesecke has previously defended the country's approach, saying countrywide lockdowns only delay the number of COVID-19 cases.

"There is very little we can do to prevent this spread," Giesecke wrote in the Lancet medical journal earlier in May.

"A lockdown might delay severe cases for a while, but once restrictions are eased, cases will reappear.

"I expect that when we count the number of deaths from COVID-19 in each country in one year from now, the figures will be similar, regardless of measures taken."

If New Zealand, which has half the population of Sweden, had taken a similar approach to try and achieve herd immunity, there could have been about 2000 deaths instead of just 22 so far. But Jackson says that number for Aotearoa could possibly have risen as high as 30,000 to achieve herd immunity.

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