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Analysis Shows Covid-19 Largely Contained in Iceland

Population genetics

(National Human Genome Research Institute, NIH)

15 Apr. 2020. Aggressive early testing combined with contact tracing and self-isolation in Iceland appears to be slowing the spread of Covid-19 infections, according to a genetic analysis. The population study in Iceland was conducted by the company deCode Genetics, a division of drug maker Amgen, with the findings appearing in yesterday’s issue of the New England Journal of Medicine.

deCode Genetics, in Reykjavik, collects data from 160,000 volunteers in Iceland, about half the country’s adult population. The company also assembles a genealogical database for the entire country going back 1,000 years to Iceland’s founding as an independent nation. These extensive data sets, combined with the high quality of universal health care in Iceland, says deCode, makes it possible to study most common diseases on a large scale, minimizing the selection bias that can occur in larger and more diverse populations.

For tracking Covid-19 infections, a team from deCode Genetics, Iceland’s public health authorities, and the national hospital screened 1,221 residents in January through March 2020 considered at high risk of Covid-19 infections, both those with characteristic symptoms or in contact with others having the disease, as well as travelers from regions where the disease was prevalent. The researchers also sampled 2,797 residents from Reykjavik’s general population largely without Covid-19 symptoms or at most a mild cold.

The deCode team took nose and throat swabs from study participants, then analyzed for SARS-CoV-2 viral RNA by the company’s genetic sequencing facilities. In addition, participants testing positive provided their contacts in the 24 hours before contracting the virus, as well as answered questions about their symptoms and recent travels.

The results show of the high-risk sample, 13 percent tested positive for Covid-19 infections, while less than 1 percent (0.6% to 0.8%) tested positive in general population samples, either recruited for the study or answering an open invitation to take part. Those testing positive were more likely to be male than female, and older than 10 years. In fact, no children under the age of 10 tested positive in the study.

Many of the early infected Icelandic participants were international travelers who visited northern Italy or Austria, which reported strains resembling SARS-Cov-2 viruses found in those regions. As the three-month study period progressed, however, more cases emerged with viral types resembling those found in the United Kingdom. Only 11 participants showed infections from the type of virus found in the Western U.S. or Asia.

The analysis shows during the last two weeks of March, the infection rate in Iceland stayed low and stable. The authors attribute the low rate of infection in the general Icelandic population to aggressive testing by the country’s health authorities. Testing for Covid-19 among people possibly exposed to the virus began a month before the first confirmed case in Iceland. Moreover, the country requires self-isolation and quarantines among those exposed to Covid-19, as well as social distancing by the general population.

“In attempting to carefully map the molecular epidemiology of Covid-19 in Iceland,” says deCode’s CEO Kari Stefansson in a company statement, “we hope to provide the entire world with data to use in the collective global effort to curb the spread of the disease.”

Stefansson is also the paper’s senior author. who with his colleagues recommends, “that unless we continue to test and isolate, track contacts, and quarantine, we are likely to fail in our efforts to contain the virus.”

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