Few signs of ‘hidden’ Corona infection

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A survey of nearly 30,000 Norwegians has revealed surprisingly little “hidden” infection among Norway’s general population. It’s the first good news after weeks of mass testing resulted in record numbers of confirmed Corona virus cases.

Professor Torkjel Sandanger (left) and Assistant Professor Erik Eik Anda are all smiles after the testing of nearly 30,000 Norwegians showed little signs of undetected Corona infection within the general population. PHOTO: UIT/Stig Brøndbo

The experts at state public health institute FHI (Folkehelse-institutt) had feared that the amount of underlying infection among Norwegians who have never been tested would be much higher. They’ve long been concerned that an earlier lack of virus testing capacity, along with a reluctance by some to be tested, could suggest underreporting of Covid-19 cases.  Many people may well have been walking around with the virus without realizing it, and thus passing it on to others.

FHI officials, in cooperation with the University of  Tromsø/Norway’s Arctic University, therefore launched the survey in an effort to gauge the amount of infection that’s gone under the radar. The university sent text messages to 110,000 Norwegians over the age of 16, chosen at random around the country from Norway’s official log of all residents, Folkeregisteret.

Testing kits and questions
Recipients were asked if they’d be willing to find out whether they’re immune to the Corona virus. If so, they’d be sent a series of questions along with a home-testing kit to produce a drop of blood to be sent back to the university.

Around 31,500 responded. Fully 88 percent of them sent in blood samples that, when analyzed, left the researchers mighty pleased. “The national, average results from the study showed that 0.9 percent had antibodies in their blood,” said Professor Torkjel Sandanger, who led the research along with Assistant Professor Erik Eik Anda. “That means the clever people tracking infection in Norway have found most of those who’ve been infected.”

The university released its findings on Thursday. Sandanger also praised all those who’ve tested themselves and who’ve done what the infection trackers told them to do, when isolation or quarantine was needed. “Until now, we’ve only had an overview (of infection) from those who have tested themselves for Covid-19, because of symptoms or their own close contacts,” Sandanger added. “Since many people may have had the virus without realizing it, we wanted to find out how many in Norway have actually been infected.”

Young men at risk
The researchers found varying levels among age groups, with more prevalence among young Norwegian men and residents of Oslo and Bergen. Overall, however, Norway distinguished itself on a national level with much less hidden infection than in many other countries. “In Norway, we’re finding nearly everyone who gets infected,” Sandanger said. That compares to only one in eight cases in Europe as a whole.

“This is good news,” said Frode Forland of FHI. “It indicates that we have relatively little infection that hasn’t been detected within society.”

The researchers think the low level of infection that does go undetected is tied to Norway’s small population in large areas of the country. They also believe the vast majority of Norwegians have abided by both local and national Corona containment measures, while effective testing procedures have played an important role.

“This indicates Norwegian authorities’ strategy has functioned very well,” Sandanger told NRK. “Those tracking down people exposed to infection have also done a good job.”

NewsInEnglish.no/Nina Berglund