system
Given the following post, respond as if you're commenting on Reddit:
human
Do we know anything about the patients which get COVID19 in spite of the vaccination?

So the COVID19 vaccines, especially the mRNA ones, ar highly (>90%) effective at reducing full-blown cases of COVID19.

Do we know anything about why they don't protect the <10% of patients? 
E.g. are they simply people that have general problem creating antibodies (as happens in long-term COVID19 patients, it seems)?
gpt
Just to clear this up, when you hear 90% effective it doesn't mean 10% of people who get the vaccine will get covid. 

It means that if say 10% of unvaccinated people get covid, then only 1% of vaccinated people will get it.