I didn't see the case numbers but I've inferred to arrive at 90% that there were 9 cases in vaccinated group vs 85 in controls. (95% C.I. 80-99%)
Very interested to see forthcoming results from competitors that don't face the -80 degrees issue.
Those are the numbers that matter, statistically. If the total number of people in the study were 2 thousand or 2 billion doesn't enter into the math.
It affects confidence, and potentially the result of the test entirely. I won't be more specific because stats was never a strong suit and my memory's hazy, but I remember enough to know it matters!
It does seem low for the US where you have 3% of the population had disease already in 2020. Perhaps more data came from Germany? Or it could be they measure not just PCR +ve results, but antibody levels and/or severe symptoms?