[jimjamuser]

Originally Posted by blueash

You are mistaken in your explanation of how the effectiveness of the vaccine was calculated. In the Pfizer vaccine study there was ~95% protection against clinical COVID meaning the patient was ill with COVID whether mild moderate or severe. It did not look at subclinical disease so some vaccinated persons might have caught COVID but not developed any symptoms but still be capable of spreading the virus to others.

The other way to express this is that for every 20 people who get sick with COVID, if they'd gotten the vaccine 19 would not have gotten sick. You are correct that the duration of immunity from being vaccinated is unknown. It will be important to understand that ongoing post-vaccination studies will partly answer that in the next year. One small factor is that while there is lots of COVID in the community, those who have been vaccinated may encounter the wild virus which will act as an immune booster for them. Once there is far less disease circulating that natural booster from exposure will disappear and later follow up studies may show a shorter duration of protection than the earlier studies.

This happened with chicken pox vaccine which when first offered seemed to be giving extremely long protection without breakthrough cases in those vaccinated children. But they were going to school with lots of unvaccinated kids and being exposed to wild chicken pox. Once almost every child was protected there began to be seen more breakthrough cases and a booster dose was recommended. That plan has worked very well.

Thank you!