Between a tenth and a third of Stockholmers may have antibodies for Covid-19

According to data collected by the Karolinska Institute from blood donations in Stockholm, 11 out of 100 people have developed antibodies for the novel coronavirus – but the actual number may be much higher. In a press conference on Tuesday, the Public Health Agency announced that a plateau may have been reached.

Sweden’s relaxed response to the Covid-19 pandemic has made headlines around the world. Measures have remained minimal. The only restrictions in place are that high schools and universities have been recommended to close and  gatherings have been limited to 50 people.

Anders Wallensten, Deputy State Epidemiologist at the Public Health Agency, said on Tuesday that Sweden had registered close to 500 new cases on Monday – putting the total tally at 15,322. The number of dead nationwide is 1,765.

The Karolinska Institute, a research-led medical university close to Stockholm, has, for the past two weeks, been surveying antibody development in a hundred samples of blood donations. The raw results were that eleven people tested positive for antibodies – but some factors indicate that the number affected could be threefold.

“We are happy to have a test that we know is okay. It is not 100 percent sensitive, it has sensitivity of 70-80 percent. Some will test negative even though they have had it. But no one will test falsely positive”, Jan Albert, the Swedish microbiologist responsible for testing, told national public broadcaster SVT on Monday.

Tom Britton, professor in mathematical statistics, assumes that there are a larger number of recovered and asymptomatic cases, believing a third of Stockholmers to already have been infected.

“In about a month, the worst spread of infection will be over in Stockholm. Then we will be close to the so-called herd immunity”, Britton told SVT.

While saying that Sweden may have already reached a plateau in infections, the Public Health Agency, Civil Contingencies Agency and the National Board of Health and Welfare advised caution in their mutual press conference. They were reluctant to announce exact dates for lifting restrictions, and also said that some problems may lie ahead.

“We have a shortage of some protective equipment, especially safety overalls”, Taha Alexandersson of the National Board of Health and Welfare said. “We are trying to order more, even with a global shortage”.

She stressed that another focus area was the need to create more disposable intensive care units. At the time of writing, Sweden has 1,125 intensive care beds – with 533 of these being filled by corona-infected patients at the time of writing.

The Civil Contingencies Agency has received criticism for delaying a coronavirus tracing app in development. Morgan Olofsson, communications officer for the agency, said that it is “almost done” but that an exact launch time can not be announced.

“Most of the app is working, it’s about embedding it. We are having good cooperation with other agencies and will launch it as soon as possible”, he said.

Asked by a Euronews reporter on what the main strengths of the Swedish approach were, Wallensten answered that it is a strategy that has greater longevity than a full lockdown.

“It is a big question, but if you are looking for advantages, one is that voluntary restrictions can be upheld for a longer time.  If you close completely there is more stress on the economy – this is more acceptable by the people in general. It also feels more reasonable”, he said.

Wallensteen also added that around a third of the population of the Stockholm region will have been infected by May 3. While Wallensteen denied that herd immunity was a direct goal for the agency, state epidemiologist Anders Tegnell has previously praised the strategy, seeing it as the only reasonable response. According to Healthline Media, a US-based health information provider, herd immunity can be achieved at 40 percent infected – but in most instances it would require an infection rate of 80 – 95 percent.

The outbreak has not been as intense in Skåne, with 550 confirmed cases and 46 fatalities. On Tuesday, Skåne Regional Council announced that medical personnel would be tested throughout the region, starting with Helsingborg. The council’s spokesperson Maria Wogensen confirmed to The Perspective that testing would soon commence in Lund, but could not say when.

The Perspective is awaiting a response from the council on whether a similar blood donations test as the one in Stockholm will happen in Lund.

This article may be updated.

Fredrik Fahlman
Luke Sandford