The, e.g. “32 million cases of flu” reported by the CDC is not based on 32 million positive test results. It’s extrapolated based on a factor of how many cases require hospitalization, and how many people seek medical care, which itself is based on antibody and behavioral surveys.
> The numbers of influenza illnesses were estimated from hospitalizations based on how many illnesses there are for every hospitalization, which was measured previously (5).
> Some people with influenza will seek medical care, while others will not. CDC estimates the number of people who sought medical care for influenza using data from the 2010 Behavioral Risk Factor Surveillance Survey, which asked people whether they did or did not seek medical care for an influenza-like illness in the prior influenza season (6).
After reading more about it [1] you almost wonder how much better than a WAG (“Wild Ass Guess”) it really is.
Frankly I am finding this whole area of medical science entirely underwhelming relative to the potential impact to lives and economies of the world.
The problem is we don't have the same data for this virus yet.