These Phase III vaccine trials also do weekly symptom monitoring. In order to qualify for lab evaluation for COVID-19, there's criteria for how many symptoms are required and for how long.

The Pfizer trial results were based on 170 confirmed cases but there were “3410 total cases of suspected, but unconfirmed covid-19 in the overall study population, 1594 occurred in the vaccine group vs. 1816 in the placebo group.”[1]

[1]: https://blogs.bmj.com/bmj/2021/01/04/peter-doshi-pfizer-and-...

> there's criteria for how many symptoms are required and for how long.

Interesting, why? In the UK at least, they now hand out Covid tests like candy.

> But when looking at who got Covid, the numbers are tiny.

True, of a sample size of 40,000 a small number got COVID. Thankfully it is big enough as the efficacy numbers have proven very accurate in real world measurements.

> Thankfully it is big enough as the efficacy numbers have proven very accurate in real world measurements.

But are you considering the fact that breakthrough infections are counted using comparitively low CT values in RT-PCR tests?

Do we know how it will affect the positive rates of the test?

> In the end you are comparing who had vaccine/placebo on a group of O(100) people.

I guess this is what people were saying about Absolute vs Relative risk reduction. If that is so, your explanation makes it much more clear.