One recent study looking at the case fatality rate in the New York region from March to August found that the death rate for those admitted to the hospital dropped from 27% to 3%. They also found many possible reasons for this dramatic decrease. One is the fact that in March New York hospitals were overwhelmed with COVID cases. They did not have enough ICU beds or ventilators, and doctors were crushed beneath the initial wave of cases of a disease they had no experience with. So simply “flattening the curve” and reducing pressure on hospitals is one important factor.
The most encouraging reason for the decline is the steep learning curve of knowing how to treat those who are seriously ill with COVID. Doctors have learned through direct experience how to better manage COVID patients.
This study also finds that there is likely a significant effect from earlier diagnosis. We are doing more testing than in March, which means some people will be diagnosed at an earlier phase of their illness, be treated earlier, and have better outcomes. This is a good thing, and is another reason to have aggressive testing – to prevent spread of the virus, but also to treat people early.