Finland's antibody tests indicate COVID infections much higher than official data during first wave

Slideshow ( 2 images )

HELSINKI (Reuters) - Finland likely had up to five times more COVID-19 cases than its official numbers showed during the first wave of the pandemic between March and May, its public health authority THL said on Thursday, citing results from its antibody tests.

The official COVID-19 case numbers are based on diagnostic tests taken from the nose or throat of a person with symptoms while antibody tests are performed on a blood sample to find out whether a person has previously been infected.

“There were roughly 1.5 to 5 times more infections compared to confirmed clinical cases,” THL said in a statement.

The difference in the numbers is largely explained by the lack of testing capacity during the first wave of infections, THL’s head of health security Mika Salminen said.

THL in April launched its own random antibody testing through Finland’s main hospitals to try and track the disease’s true spread, including among those who contracted the illness without showing any symptoms.

Salminen said the results also indicated a smaller share of young people contracted COVID-19 during the first wave than now.

THL also looked at comparative data available from antibody tests in other countries, Salminen said, noting Spanish figures were much higher.

“During the spring’s epidemiological peak, a remarkably high share of cases, up to a 10-fold share, went undetected in Spain,” he said.

Reporting by Anne Kauranen; Editing by Alexandra Hudson