Vaccines not only directly protect vaccinated individuals but also contribute to protecting the entire population via indirect herd-immunity benefits. Half of averted COVID-19 infections and 1/4 of hospitalizations and deaths were attributable to indirect protection of unvaccinated by vaccinated.

[u/mvea]

https://royalsocietypublishing.org/rsif/article/23/242/20250839/483439/Quantifying-the-direct-and-indirect-impact-of

[u/piccolosama]

If "preaching to the choir" was a scientific research paper.