In this population-based study in Iceland, very few (< 1%) of people in the general population screened positive for SARS-CoV-2, compared to more than 13% of those targeted for testing.
In Iceland, testing was targeted to those who were at high risk for infection (symptomatic, recent travel to high-risk countries, or contact with infected persons). Researchers also conducted population screening using two strategies: an open invitation to 10,797 persons and random invitations to 2283 persons.
As of April 4, 13.3% of 9199 persons who were recruited for targeted testing had positive results for infection with SARS-CoV-2. Of those tested in the general population, 0.8% in the open-invitation screening and 0.6% in the random-population screening tested positive for the virus. A total of 6% of the population was screened.
Most persons in the targeted-testing group who received positive tests early in the study had recently traveled internationally. In the population screening, no child under 10 years of age had a positive result, compared to 0.8% of those 10 years of age or older. The percentage of infected participants in population screening didn’t change significantly during the 20-day duration of screening.