Close to Peak COVID?

An analysis of confirmed cases and estimated infections in Ireland in September 2020

Photo by Will Turner on Unsplash

At the time of writing the 7-day rolling average of confirmed cases in Ireland was just over 200 cases per day and growing. Given that our peak was 903 cases per day back in April, this suggests we are now exceeding 22% of this peak. Some people have questioned whether this is a fair comparison, and there are reasons to believe that it may not be:

1. We are much better at finding cases now than we were in April, because our testing infrastructure is a lot better; tests have reached approximately 10,000 tests per day recently, compared with about 5,000 tests during the peaks of spring.
2. Test positivity rates are much lower today than they were in spring, which means we should be missing fewer true infections now; test positivity peaked at more than 20% during April, compared with current rates of less than 2%.

It turns out that although current cases do exceed 22% of their past peak, the current number of estimated true infections is just 14% of its past infection peak, which is likely to be a more realistic relative assessment of our current outbreak.

The rest of this article explains why this is the case, but let’s be clear: whether its 22% or 14%, the point is that…