I was looking through covidnow and was a bit puzzled.

To calculate positive cases per 100 people the last 6 months is pretty easy. I assume you just take the total positive cases the last 6 months and and divide it by total population. Total population I assume is not exact real-time number, but probably from last census or any of its acceptable projections. You would end up with an agreeable figure.

To calculate positive cases per 100 people the last 6 months by gender would be similar. Take total cases the last 6 months. If you go case by case you can easily categorize each case into respective gender. Take that and divide that by total population by gender based on the last census or any of its acceptable projections. You would end up with an agreeable figure too.

What puzzles me is when I look at the positive cases per 100 people the last 6 months by vaccination status (none/partial/full). For the numerator you can do the same thing by taking the total cases the last 6 months and go cases by case and identify at the time of testing whether the person was not/partially/fully vaccinated. But how about the denominator? The number of population that are not, partial and fully vaccinated keeps changing over the course of 6 months. The number today is not the same compared to 6 months ago, 5 months ago, 4 months ago etc. What would you divide with?