Tests provide new picture of the spread of the virus

13 May 2020

With the help of volunteer doctors, the researchers tested over 6,000 individuals who work in care homes.

Two recent studies testing for antibodies against the coronavirus SARS-CoV-2 provide a new picture of the spread of virus in Sweden. “To gain a more realistic picture of the spread of the virus in Sweden, we need to perform more tests,” says Åke Lundkvist, professor of virology at Uppsala University.

His research team at Zoonosis Science Center (ZSC) at the Department of Medical Biochemistry and Microbiology (IMBIM) is focusing heavily on research about the corona pandemic. In addition to research on possible COVID-19 drugs, they are also focusing on finding and developing tests that detect antibodies against the virus and to understand what their function is.

Åke Lundkvist, professor of virology who leads
Zoonosis Science Center. Photo: Annica Hulth

The goal is to create a more realistic picture of the spread of the virus in Sweden but also to better understand the role of the antibodies during recovery and for immunity after the infection.

“Once we realised that the virus had become epidemic in Sweden, that is, that it is something that we will have to deal with for some time, we gradually refocused our research,” says Åke Lundkvist, professor of virology who leads ZSC.

The researchers have assessed one of all the rapid antibody tests sold online by analysing blood samples from 100 donors from 2018, that is, before the virus was found in humans, to rule out false reactions. The team worked at a record pace and published a scientific article on the rapid test as the first research group in Sweden.

“We did this because the need was so overriding. With the help of volunteer doctors, we tested over 6,000 individuals who work in care homes. We have now compiled the results from the first 1,000, and we will publish this data as soon as possible,” says Lundkvist.

The infection may have come from staff

The study shows that as many as 23 per cent of the 1,000 care workers are or have been infected.

“This shows that the elderly who have died at elderly care homes may have been infected by staff, since the recommendations specified that they were not to have respiratory protection other than when working with sick patients. This is why these results are so important. Among the approximately 230 who had antibodies to SARS-CoV-2, almost half had no symptoms at all. So they went to work anyway because they felt completely healthy.”

In addition to rapid tests, the researchers have developed a super-sensitive antibody test based on the Luminex technique. This test is quantitative, unlike rapid tests which only give a positive or negative answer.

Recently, tests were conducted on 454 individuals in Stockholm. These tests showed that only 7.5 per cent had antibodies, which differed significantly from the calculations made by experts at the Public Health Agency.

“We will wait to say more about how immunity is progressing until we have conducted another round of tests in late May.”

Difficult to determine flock immunity

The study also showed major differences in the spread of infection between different parts of Stockholm. Many people are hoping for flock immunity, but Åke Lundkvist finds it difficult to know what that means in this case.

“No one knows how the spread of the virus will develop and what it takes for flock immunity to kick in. We can only speculate. With the flu, 60 to 70 per cent is usually considered necessary to achieve flock immunity. Today, when we vaccinate half the population, ‘only’ between 800 and 1500 people die in Sweden each winter. Before the vaccine came in the 90s, 2000–4000 died of the regular seasonal flu. This numbers won’t stop there in this pandemic.”

Åke Lundkvist worked at Karolinska Institutet and at the Swedish Institute of Infectious Diseases before becoming a professor at Uppsala University in 2014. A year later, a biosafety level 3 laboratory was opened at the Uppsala Biomedical Centre (BMC), and Åke Lundkvist and Björn Olsen, professor of infectious medicine, built up a research team with many different expertises in what was later named ZSC.

“In our team, we have virologists, bacteriologists, entomologists, drug experts, veterinarians and medical researchers. What is amazing is that we now have a collection of people in our Zoonosis Lab that is perfect for researching the SARS-CoV-2 virus.”