Although the Covid vaccines aren't perfect, in the US they greatly reduced the number of Covid cases, the severity of Covid cases, and the number of Covid deaths. How do we know? by comparing illness among the vaccinated with illness among the unvaccinated.
In 2021, the 75% of Americans fully vaccinated produced under 20% of the Covid deaths, while the 25% unvaccinated Americans produced over 80% of the Covid deaths.
In 2021, the 75% of Americans fully vaccinated produced under 31% of Covid cases; while the 25% unvaccinated Americans produced nearly 70% of Covid cases.
This means the US unvaccinated had a 5X higher chance of contracting Covid compared to the vaccinated per capita, and that overall the unvaccinated had about a 15X higher probability of Covid death per capita.
Note: since 'Long Covid' occurs in 15% to 25% of Covid cases, that means there is also a 5X higher prevalence of Long Covid per capita among the unvaccinated.
Source https://www.cdc.gov/mmwr/volumes/71/wr/mm7104e2.htm
More details: https://similarworlds.com/disease-illness/vaccines/4268857-Covid-Vaccine-effectiveness-data-from-the-US-2021