It seems unlikely that any college or university will be 100% vaccinated: there is a small, but non-trivial proportion of the population for whom the vaccine is medically contraindicated. Those people- who can be students, staff, admin, or faculty- will have exemptions certs. There is another proportion of the population who do not choose to be vaccinated for genuine religious reasons, for whom many universities give exemptions. And there is yet another proportion of the population who are anti-vaccination in general and/or anti-covid vaccine in particular for their own reasons (political, social, uncertainty, etc), some % of whom will find a back door way to get an exemption. Put those three groups together, and include the % of Americans who are covid-vaccine reluctant and it seems unlikely that your student will be in a 100% vaccinated environment.
Of course, only you know what % vaccinated population you are comfortable with for your child’s educational environment. Also, schools / unis that do not require vaccination (there are some that are very clear that they will not, and there are some states that have mandated that public universities may not) my still require regular testing.