Just 7% of people in Stockholm had developed coronavirus antibodies by the end of April, research by Sweden's public-health agency found.
- A new study by Sweden's public-health agency found that just 7% of people in Stockholm had developed coronavirus antibodies by the end of April.
- Swedish forecasters had predicted that up to half of the population would catch the virus by May.
- Experts say at least 60% of a population needs to catch the virus before any protective immunity can be achieved.
- Tom Britton, a professor who helped develop the agency's model, told a Swedish newspaper that it was "surprising" that the forecasts "are so wrong."
- Visit Business Insider's homepage for more stories.
A new study suggested that only a small percentage of people in Sweden's capital, Stockholm, had developed coronavirus antibodies, casting doubt over whether the country's avoidance of strict lockdown measures is helping the population develop a significant level of immunity.
The study, based on 1,100 tests across Sweden and carried out by the country's public-health agency, found that just 7.3% of people in Stockholm had developed antibodies, Reuters reported on Wednesday.
Experts say populations can achieve so-called herd immunity to a virus when about 60% of people have caught it.
Tom Britton, a professor who helped develop the agency's forecasting model, acknowledged that the calculations may have been wrong.
"It means either the calculations made by the agency and myself are quite wrong, which is possible, but if that's the case it's surprising they are so wrong," he told the Swedish newspaper Dagens Nyheter, according to The Guardian. "Or more people have been infected than developed antibodies."
Britton had previously suggested that about half of the country could become infected by the end of April.
Sweden this week overtook the United Kingdom, Italy, and others to become the country with the highest number of coronavirus deaths per capita.
Unlike most other European countries, Sweden has not implemented strict, wholesale lockdown measures in response to the coronavirus pandemic. Instead, the country has largely allowed businesses to remain open and students to attend school.
It has also taken a more relaxed approach to testing than most other countries. The Swedish government has a modest target of carrying out 100,000 tests a week and has focused mainly on testing healthcare workers and people who are hospitalized, Reuters said.
The Swedish government has said it is not aiming only for herd immunity but that it could slow the spread of the virus enough to ensure that the capacity of its health service is not breached.
Herd immunity 'is a long way off, if we ever reach it'
The new findings challenge proponents of the herd-immunity strategy.
Bjorn Olsen, a professor of infectious medicine at Uppsala University, told Reuters, "I think herd immunity is a long way off, if we ever reach it."
However, Anders Tegnell, the country's head epidemiologist, told reporters that the findings reflected the situation in April and that he thought about 20% of people in Stockholm had now caught the coronavirus, The Guardian reported.
The Swedish government has insisted that its strategy will pay off in the long run.
Earlier this month, Tegnell, who leads the public-health agency, told the Financial Times that while countries that imposed strict lockdowns would likely suffer large second waves later in the year, Sweden's would be smaller.
"In the autumn there will be a second wave," Tegnell said. "Sweden will have a high level of immunity and the number of cases will probably be quite low."
Tegnell said that Finland, Sweden's neighbor, "will have a very low level of immunity."
"Will Finland have to go into a complete lockdown again?" he said.
Sweden's public-health agency has predicted that 40% of people in Stockholm will have caught the COVID-19 virus by the end of this month, The Times of London reported on Thursday.