Thread by @apsmunro

Here is a good lesson in basic epidemiology

This data is difficult to interpret in a number of ways:
1. There is no denominator, either of institutions or populations
2. It counts the number of outbreaks, not cases
3. It doesn't tell you who had the infections

This matters

1/5

https://twitter.com/DrZoeHyde/status/1338456425102655488

An extreme example of why this is important from earlier this year

After lots of excitement about outbreaks in schools it turned out the median number of children involved was...

Zero

2/5

https://twitter.com/apsmunro/status/1291763008386072576?s=20

For some denominator context there are:

- 24,000 schools (9 million pupils) not inc. university
- 11,000 care homes (410,000 residents)
- 117 prisons (79,000 prisoners)
- 26,000 restaurants (many not/partially open)

We are comparing apples and oranges

Epidemiology 101

3/5

These numbers are more useful for comparing relative trends over time, where educations settings have actually remained remarkably stable

Rates have unsurprisingly fallen in other locations which were closed over lockdown

But there is more to consider

4/5

Rates are high in secondary schools at the moment, lagging behind adult cases numbers which fell during lockdown (in Hubei kids numbers lagged 19d behind adults)

onlinelibrary.wiley.com/doi/10.1111/jp…

Hopefully this plus impending school holidays will help get numbers down again

5/5