You don’t need germ theory to notice that infections tend to spread via contact or proximity to the infected, something included in the miasma theory for centuries. Vaccination as a widespread practice started in the late 1700’s, predating germ theory by about 40 years. While the initial introduction of smallpox was accidental, settlers later intentionally spread it as a form of early biological warfare:

While not every smallpox outbreak was deliberately caused by white settlers, enough evidence exists to clearly demonstrate that more than once actions were taken to intentionally facilitate its spread. In many of these cases, through their own words, people demonstrate depraved indifference, if not intentional genocide.