system
Given the following post, respond as if you're commenting on Reddit:
human
How do epidemiologists determine whether new Covid-19 cases are a just result of increased testing or actually a true increase in disease prevalence?
gpt
One metric is the rate of positive tests. Let’s say you tested 100 people last week and found 10 cases. This week you tested 1000 people and got 200 cases. 10% to 20% shows an increase. That’s especially the case because you can assume testing was triaged last week to only the people most likely to have it while this week was more permissive and yet still had a higher rate.

Another metric is hospitalizations which is less reliant on testing shortages because they get priority on the limited stock. If hospitalizations are going up, it’s likely that the real infection rate of the population is increasing.