James J. Stock et al
In the early stages of the pandemic, testing targeted individuals whose symptoms and/or jobs placed them at a high presumed risk of infection. This potentially results in a high proportion of cases going undetected. In an update of our April paper, we use public data from two Icelandic testing regimes during the first month of the outbreak and estimate an identified interval for the undetected rate. Our main approach estimates that the undetected rate was between 89% and 93% before the medical system broadened its eligibility criteria and between 80% and 90% after.
