Very few vaccinations offer immunity to “infection” (see further below). Most vaccinations are designed to provide protection against the Effects of infection.
We get infected by the same illnesses all the time; that is the whole point of having immunity (protection) against previous infection, which vaccinations are designed to mimic.
[Heading:] "Israel says the Delta variant is infecting vaccinated people, representing as many as 50% of new cases. But they're less severe.", Jun 24, 2021:
https://www.businessinsider.com/israel-50-of-delta-variant-cases-vaccinated-severe-2021-6
Most vaccines are not designed to prevent infection but are designed to prevent serious symptoms. Research is still underway regarding whether the Coronavirus vaccines prevent infection:
https://www.nature.com/articles/d41586-021-00450-z
Robert 