It has appeared since the start of the epidemic that there may be reason to believe that not all people with exposure became infected and that many infected persons were asymptomatic or had such mild symptoms that they sought no medical care. How big these groups are is a critical question for understanding how the epidemic might spread and what mitigation of spread measures are appropriate. A town in Germany has done significant testing of its population for antibodies to the virus and found that about 15% of the population had been infected, although most were asymptomatic or had a mild illness. (German Study) While that isn’t at a level that would significantly slow virus transmission, it is a meaningful step to that point. In addition, the new data indicates that in this town, the fatality rate as a percent of all infections was no more than .4% and likely lower. Other research looking at antibodies or virus in blood donations has also found unreported cases. And in perhaps the oddest study, researchers looking for virus in sewage in Massachusetts also found indications of substantially more cases than have been reported.
A combined large scale testing program for antibodies and for current coronavirus infection would be crucial for determining how far into the population the virus has spread. It would allow individuals with antibodies to resume normal activities, including work. It would inform how aggressive we need to be in efforts to mitigate spread. I can’t understand why with all the money flying around in stimulus and spending packages, a substantial amount can’t be committed to an immediate testing program. The economic payback would be enormous. So we should all be pushing for that program now.