Iceland has a fortuitous combination of factors making it about the best place in the world to come by good data on coronavirus. It’s an island, it has a small homogenous and cooperative population, and it is home to deCODE Genetics:
In Iceland’s case, it has done this through a combination of rigorous testing and tracing. Authorities say Icelanders are heeding social distancing recommendations.
Stefansson said Iceland’s randomized tests revealed that between 0.3%-0.8% of Iceland’s population is infected with the respiratory illness, that about 50% of those who test positive for the virus are asymptomatic when they are tested, and that since mid-March the frequency of the virus among Iceland’s general population who are not at the greatest risk – those who do not have underlying health conditions or signs and symptoms of COVID-19 – has either stayed stable or been decreasing.
Whatever the R0 of coronavirus is, the consensus seems to be that it is higher than that of the seasonal flu. It’s estimated that the flu infects around 10% of the populations of Western countries each year, yet Iceland’s coronavirus infection rate is estimated at under 1%.
Because of social distancing and sheltering in place, right? If social distancing and other preventative measures have kept coronavirus from spreading to even 1% of the population during flu season, we should expect to see drastically lower levels of influenza infection rates this year as well, shouldn’t we? We’re only talking a month or two in for coronavirus compared to a full six month season for the flu, but even if over the duration of the flu season coronavirus infected just 5% of the population on account of social distancing and other preventative measures, influenza rates would conceivably be even lower than 5%–somewhere between 2%-3% on an R0 for coronavirus around 2.5 and for the flu of around 1.3.
That should be detectable in flu testing results for the 2019-2020 season, shouldn’t it? Even though flu tests aren’t ubiquitous, differential results from this year to last among high-risk groups for which flu testing is fairly common, like pregnant women, would conceivably provide sufficient data to tell.
If social distancing is effective, Iceland and Norway should have considerably fewer flu infections per capita than Sweden does this year. If, on the other hand, flu rates are similar to rates in other years, it would seem to imply that social distancing hasn’t done much and that coronavirus isn’t nearly as contagious as was feared early on. We should see something similar in the US, with flu season being far more mild in California, Washington, and New York this year relative to previous years, while flu rates in states like the Dakotas that have not issued any restrictive measures should be on par with those of other years.
The third possibility–that the infection rate is much higher and the mortality rate much lower than generally believed–is unsupported by the Icelandic results. Other jurisdictions, including some in the United States, are in the process of conducting randomized testing of their own, so we’ll see if the low total infection rate holds in other places.