"No country… 更多 knows the total number of people infected with COVID-19. All we know is the infection status of those who have been tested. All those who have a lab-confirmed infection are counted as confirmed cases.This means that the counts of confirmed cases depend on how much a country actually tests. Without testing there is no data.Testing is our window onto the pandemic and how it is spreading. Without data on who is infected by the virus we have no way of understanding the pandemic. Without this data we can not know which countries are doing well, and which are just underreporting cases and deaths."