FIGURE 2.

Testing statistics per country (Switzerland, Spain, Iran and Pakistan, January-July 2020). (A) Tests per million population. The first gray dashed lines represent the day that the World Health Organization declared the pathogen a subject of international concern and the second line represents the first day of a COVID-19 case was detected in each country: February 23 in Switzerland, January 31 in Spain, February 18 in Iran, and February 24 in Pakistan. In Spain, the day that the WHO declared the pathogen of international concern was 1 day before the first case was found in Spain, and therefore the difference between the first two lines is indistinguishable in the graph. The third gray line shows the day when the WHO declared the pandemic: 11 March 2020. (B) Positivity rate, measured as the fraction of all tests that are positive each week. (C) The relationship between test intensity (measured as tests per million population) and the positivity rate each week. In Switzerland, the COVID-19 Datahub did not have testing numbers before epidemiological week 22, but the Swiss government provides those estimates for download, so we have combined both datasets [66]. In Iran, the COVID-19 Datahub did not have testing numbers before epidemiological week 15, but we knew that there would be 78,434 tests administered on week 16, and we found a publication that stated that there were about 600 tests per day done at the end of the first week after the first case, and 6000 tests performed by the end of the first month [53]. We therefore took a linear interpolant to calculate the number of tests that were done in those first 8 weeks.