As per the U.S. Supreme Court -- vaccines have been forcefully mandated since 1905. It is not in any way unconstitutional.
Jacobson v. Massachusetts, 197 U.S. 11 (1905), was a United States Supreme Court case in which the Court upheld the authority of states to enforce compulsory vaccination laws. The Court's decision articulated the view that individual liberty is not absolute and is subject to the police power of the state.
https://en.wikipedia.org/wiki/Jacobson_v._Massachusetts
You beat me to it.
I grew up in a military family. We moved around a lot. All the states (seven of them) that we lived in...all had some kind of a mandatory vaccination law for school enrollment, school sports, organized sports, scouts, or something.
Laws that have been around since the early 1970's but my old man used to tell us kids that these laws have already existed for many many years.
As a kid, I still remember every Doctor office we visited (Illinois, Kentucky, Pennslyvania, Georgia, North Carolina, Texas and South Dakota)...the Doctor always asked my parents for the vaccination card to ensure we had the needed vaccination for their school systems.
In fact, the few times we lived abroad in another country to live off base with my old man...we were required to get the same vaccinations as the soldiers.
If we didn't have the vaccine...we got it then.

wrbtrader