The Finnish Institute for Health and Welfare’s (THL) head office in Helsinki on 21 April 2020. (Markku Ulander – Lehtikuva)

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NOT MANY PEOPLE in Uusimaa appear to have developed an immunity against the disease caused by the new coronavirus, suggests a new study conducted by the Finnish Institute for Health and Welfare (THL).

THL on Wednesday published the first results of the study of the prevalence of coronavirus antibodies in the 1.65-million-resident region, admitting that the low prevalence came as a surprise.

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“We did not expect a high prevalence, but definitely higher than this,” Jussi Sane, a chief specialist at THL, admitted to Helsingin Sanomat. “We’ll continue the study and seek to develop a clearer understanding of where we are with the epidemic in [the Hospital District of Helsinki and Uusimaa] HUS.”

HUS has accounted for 2,779 of the 4,995 laboratory-confirmed infections in Finland. It nevertheless appears that only few of its residents have produced antibodies to the new coronavirus, a process that typically takes a few weeks after the infection.

THL said in a press release it has analysed 516 of the over 1,000 samples collected for the antibody study. Screening tests found antibodies in 11 of the 516 samples, but neutralisation assays produced a positive result – indicating that the antibodies are capable of neutralising the virus – in only one of the nine initially positive samples analysed so far.

At least 3,000 have recovered from Covid-19

  • The Finnish Institute for Health and Welfare (THL) says the number of laboratory-confirmed coronavirus infections rose by 89 to 4,995 between Wednesday and Thursday.
  • The new coronavirus thereby has an incidence of 90 cases per 100,000 inhabitants.
  • The virus has claimed the lives of 211 people in Finland.
  • A total of 187 people are currently in hospital care, including 48 in critical care, for symptoms caused by the virus.
  • The number of samples tested for the virus rose by roughly 4,100 to 93,900 between Wednesday and Thursday.
  • It is preliminary estimated that at least 3,000 people have recovered from the virus. The estimate is based on the number of cases reported at least two weeks ago that have not been supplemented with updates about the course of the disease.

The sample collection began on 9 April.

“Neutralisation assays reliably measure the presence of active antibodies. These antibodies are probably also an indication of at least a short-term immunity. There is so far no scientific data on what kind of an immune reaction provides protection,” told Merit Melin, a senior researcher at THL.

THL reported only two weeks ago that the actual number of infections may be dozens of times higher than reported in Uusimaa, citing the results of antibody tests conducted on residual samples taken for reasons other than a suspected coronavirus infection.

“The latest results are based on a random-sample study launched by THL,” Melin clarified to Helsingin Sanomat.

The objective of the antibody study is to determine not only how large a part of the population have antibodies as an indicator of prior exposure to the virus, but also how long the antibodies last and whether they provide protection against serious forms of the disease.

THL on Wednesday reminded that Finland witnessed the onset of the epidemic later than many other countries in Europe. The spread of the virus has also been limited effectively with strict restrictions.

“Our first population-based results of the prevalence of antibodies matches the epidemic situation, even though there were very few antibody-positive samples,” stated Sane.

The study has since its launch been expanded to the special districts of all university hospitals, and its results will be published regularly by THL.

“It is now of great importance that those who have received invitations participate widely in the study so that our experts and decision-makers have access to the best possible assessment of the spread of the coronavirus epidemic,” underlined Arto Palmu, a research manager at THL.

Tuomas Aivelo, an evolutionary biologist at the University of Helsinki, described the first findings as good news.

“This points in the direction that there isn’t a large number of undetected cases, meaning the epidemic could well be controllable with the test-and-trace method. This is overall a good piece of news,” he stated on Twitter on Wednesday.

Aleksi Teivainen – HT

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