Estimating local covid prevalence

Post date: 2023-03-29 03:52:31

At this point in the pandemic the best measure we have of prevalence is wastewater concentrations. How do I convert that to asymptomatic positivity rate?

What I really want to know is: the likelihood that someone in a group around me has covid, eg, 1 in 10, or 1 in 50, or 1 in 200. This informs my choices of where to go and what to do.

"Case counts" and such are useless at this point, since the rise of rapid tests and the wind-down of public reporting and facilities that has happened. Bob Wachter used to report asymptomatic test positivity rates from UCSF hospitals, which is arguably the closest proxy for the likelihood that some random person near you has covid. However, I don't live in SF, and that rate is not available for my local area. What I do watch now is wastewater.

How do I convert wastewater (copies/mL) to an infection or asymptomatic rate?

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