Image: Jyrki Lyytikkä / Yle

Finland’s Institute for Health and Welfare (THL) is to start researching the spread of novel coronavirus in the country with the help of broad antibody testing.

The aim is to determine how many residents already possess coronavirus antibodies - blood proteins used by the immune system to neutralize pathogens like viruses.

In this way Finland will aim to find the 'hidden' part of the epidemic in the population, as many carriers of this novel coronavirus show mild symptoms, or no symptoms, and do not get tested.

Other countries have struggled to find reliable antibody tests, and initially at least Finland will only test a randomly-selected sample of 750 people each week.

Any positive sample will be checked again using a different test before an individual is informed they have been exposed to Covid-19, Arto Palmu of THL told Yle News.

The research will involve randomly choosing individuals to be tested - at first from residents in the capital region, the area of Finland hardest-hit by coronavirus cases so far. Initially only people of working age will be invited for a test, according to the health agency, which is carrying out the research in cooperation with the country’s university hospitals.

THL said the antibody survey will help to reveal how Covid-19 has spread as well as determine how much of the population has already had the viral infection. In other words, the testing will determine the amount of people who have recovered from the disease.

The health agency also said the tests will show the levels of antibodies in people’s bloodstreams as well as how long the virus-fighting cells remain in their systems.

THL’s research specialist Merit Melin told Yle in a live webcast on Tuesday that it’s possible 40 to 50 percent of those who have had a novel coronavirus infection were asymptomatic.

Country-wide assessment

The research will expand beyond the capital region during the spring and will also include all age groups.

The researchers' random invitations for testing will start to be sent out this week, according to Jussi Sane, a senior expert at THL, but he noted that the effort will continue for quite some time.

"The idea is to get a picture of the situation across the entire country," Sane said.

Meanwhile, Melin said many people have already had Covid-19 in Finland but because they weren’t tested it hasn’t been confirmed.

"Thanks to this research we can get the kind of information that's important for everyone. The results perhaps are not that important for individuals, but considering the country’s health as a whole, it is good to know who has been infected," Melin said.

The agency is aiming to reach 750 new test participants each week. If a test participant’s blood work indicates a presence of antibodies they will be contacted. Participation in the study is voluntary, according to researchers.

"The results of the study is one part of assessing the epidemic and will also affect [shelter-in-place and other] restrictions as well as when they can be lifted," Sane told Yle.

The study will continue throughout the year but initial results are expected by the end of this month.

Edited 8.4.2020 to define antibodies as blood proteins.