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Iceland lab’s testing suggests 50% of coronavirus cases have no symptoms

Iceland’s large-scale testing for the novel coronavirus could influence how the world understands the outbreak.

Experts have said comprehensive testing is key to controlling coronavirus, and creating a more accurate picture of the spread of Covid-19. This island-nation of 360,000 is doing just that.

As of Tuesday, Iceland had tested more than 17,900 people for the virus nearly 5% of its population. And while its National University Hospital tests people who are high-risk or show symptoms, nearly half of Iceland’s tests have been conducted by biopharma company deCODE Genetics, focusing on the the wider population.




Crucially, deCODE’s “screening program accepts everybody who is not showing symptoms and not currently in quarantine,” Iceland’s Directorate of Health said in a statement, adding that Iceland-based company was doing it on the behalf of the Chief Epidemiologist and the health agency.

DeCODE, a subsidiary of US biotech company Amgen, has so far tested about 9,000 self-selected people.

“The results of the additional tests performed by deCODE have given an indication that efforts to limit the spread of the virus have been effective so far,” the government wrote last week, adding “testing in the general population will continue to elicit a much clearer picture of the actual spread of the SARS-CoV-2 virus in Iceland.”



Some of the revelations have been stark. Although fewer than 1% of the tests came back positive for the virus, the company’s founder Dr. Kári Stefánsson said that around 50% of those who tested positive said they were asymptomatic, confirming multiple studies that show that asymptomatic, or mildly symptomatic, people have played an important role in spreading the virus.

“What it means in my mind, is that because we are screening the general population, we are catching people early in the infection before they start showing symptoms,” Stefánsson said.

“Keep in mind that the screening is now randomized, but voluntary so there is some bias in the data,” the Directorate of Health said in a statement, adding that a “randomized screening program has started and a blood serum screening for antibodies is planned.”

The work has also helped researchers to visualize the spread of the virus. “We can determine the geographic origin of the virus in every single [virus] in Iceland,” he said, adding there are specific, minor mutations for the virus that came from Italy, Austria and the UK. “There was one that is specific to the west coast of the United States,” he added.

Stefánsson wonders whether mutations in the virus are “responsible, in some way, for how differently people respond to it — some just develop a mild cold, while some people need a respirator,” or whether a person’s genetics dictates their condition.

“Or is it a combination of these two?” he asks.

His company is in a better position than most to answer that question, as it already has the medical and genotype data of nearly half of Iceland’s population.