Michael S. Rogers is Assistant Professor of Surgery at Harvard Medical School and Research Associate at Boston Children’s Hospital. He writes:
I thought I’d point out a recent report that has what could be very good news. There has long been the question of how many people are getting very mild cases of COVID-19. Up until now we’ve been relying on a test for the presence of virus (a PCR test for viral RNA). Those data have suggested that approximately half of infected individuals get symptomatic disease. However, those tests cannot identify individuals who have been infected and successfully cleared the virus. By contrast, antibody tests (also known as serological tests) can identify such people.
This preliminary study is the first of its kind and looks at a village that was at “ground zero” for the German epidemic. The authors developed a high-specificity (>99%) test for anti-virus antibodies and tested a significant fraction of the village. They found that 7x as many people were positive for antibodies as were positive for viral RNA—15% of the total population. There’s good reason to think these results could be approximately representative of the rest of the world. The case-fatality rate based on RNA tests is in the range observed in the non-overwhelmed world.
This is a small and preliminary study, but if the results are borne out by others, then the mortality rates from even the direst models have to be divided by at least 7. That’s still a lot of deaths, but (as the authors of the report indicate) it means that milder mitigation measures may be sufficient once we’ve got the hotspots (like New York City) under control. That would be very good news for the economy. Ronald Bailey’s write-up for Reason may be more accessible to a general audience and is posted here.