What do we know?
They prevent severe disease, hospitalizations and death in people infected with COVID and this is what matter most..
They help to some extent in preventing infection with COVID, but with the Omicron variants, less so.
With regard to mRNA vaccines (Pfizer & Moderna), 2 is better than 1 and 3 is better than 2. Will 4 be better than 3? The Israelis are giving a 4th dose to all adults. So far they have seen some increased immunity but not enough to prevent Omicron. Problems with these vaccines are that variants have already evaded the immunity provided and the immunity seems to fade with time.. However, the exact degree and duration of protection offered with the current 3 dose recommendation is not completely known. It seems likely that we will be getting a 4th dose at some time in the future. There is work being done on the development of more effective vaccines but the current vaccines are all that we have now.
The vaccines have been given to so many people over the past two years, that we know from this experience, that they are largely safe in the short and mid-term, comparable to other vaccines that are widely used.
Bottom Line
The current vaccines are very effect in preventing severe disease, hospitalizations and death in people infected with COVID.