US Soldiers are given many vaccines to prepare them for various diseases abroad or weaponized. Historically, refusing could result in sever penalties. I also think it's been normally questioned whether some vaccines given were experimental or rushed, but could find no explicit proof that's happened before.

Military personnel sue for use in experimental agent testing.

Experimental drugs given to soldiers during the Gulf war

See also the Burn pits, Agent Orange, CTE and other effects from prolonged exposure to crew weapons use, and the working conditions inside AC-130s and related health effects