It seemed to be rare good news in a country that has seen a stubbornly high infection rate and has inevitably raised hopes that so-called herd immunity, where an immune group protects a group still susceptible to the disease, could be near. Previous estimates have suggested that herd immunity rates when it comes to coronaviruses could be around 45-50 percent of the population.
However, critics quickly questioned the statements of the Public Health Agency.
Twenty-five Swedish doctors and scientists published an open letter attacking the government’s approach to fighting the virus and alleging that immunity rates were well below those mentioned by the agency, and possibly as low as 10 percent.
One of the authors of the letter, virologist Lena Einhorn, acknowledged that COVID-19 cases, and the death rate from the disease, are falling in Sweden, but questioned the idea that immunity is an important factor.
She cited better hygiene routines within nursing homes and the fact that many Swedes distance themselves socially in summer homes as more important factors.
“The reasons are multiple, but it is unlikely that collective immunity is playing an important role,” he told POLITICO.
She said a weakness in the Public Health Agency’s 40 percent immunity estimate is that less than half was based on positive antibody tests, which are considered a clear sign that a person has had a coronavirus and has been recovered. The remaining half of the agency’s estimate relates to less understood parts of the immune system, which are believed to result in a patient being immune, but not positive for antibodies against the coronavirus.
Einhorn said this reflects a “completely unproven assumption.”
The debate in Sweden illustrates how much remains unknown as the pandemic continues to sweep across the world. Along with the best way to measure immunity and herd immunity, there are also key questions about how long immunity lasts and, in some cases, whether it exists or not.
Swedish epidemiologist Tegnell said his agency is working on the assumption that those who have recovered from the virus are immune and that the immunity lasts for at least six months.
Speaking to POLITICO after his press conference on Tuesday, Tegnell said the uneven spread of the disease makes it difficult to measure immunity levels.
“We are now collecting a number of different samples and trying to put them together,” he said.
Sweden’s outbreak of immunity rates is the latest twist in a dispute that started when Sweden decided to go its own way in the early days of the pandemic.
Back then, while Nordic neighbors like Norway and Denmark were rapidly closing schools and businesses to stop the spread of the coronavirus, Sweden largely kept society open, saying it was looking for a slow and manageable spread of the virus.
A number of critics, some of whom are the same experts who wrote this week’s critical letter, said the government was leading Sweden to disaster.
They said that not closing early was a mistake, since it was not mandatory to make face masks and not carry out more extensive contact and quarantine tracking.
The number of deaths per million in Sweden, at 561, is below the worst affected countries in Europe, including the United Kingdom and Spain, but has now shot up to almost 12 times that of neighboring Norway and around 10 times the from Finland.
Swedes are still banned from traveling to some European nations, including the Nordic neighbors Norway, Denmark and Finland.
However, Tegnell supports his light touch approach, saying that while the exact role of immunity is difficult to pin down exactly, the recent drop in the number of coronavirus cases is good news and to some extent validates the focus of your country.
“It shows that the Swedish strategy can also establish a very rapid drop in cases in the same way that blockades have,” he said.
