But by the end of the 1800s, opposition was louder and more widespread. Some states, particularly in the West, introduced laws prohibiting vaccine mandates. Others narrowly passed mandates after intense debate.

The reasons for resistance were myriad: Some Americans opposed mandates on the grounds of personal liberty; some because they believed lawmakers were in cahoots with vaccine makers; and some because of safety concerns that were, to be fair, more grounded in reality than the modern equivalent. Vaccines then were not regulated the way they are now, and there were documented cases of doses contaminated with tetanus.

The government’s response resembled what, today, are wild conspiracy theories. Contrary to the assertions of some on the far right, the Biden administration has never suggested going door to door to force people to take coronavirus vaccines. But in the 1890s and 1900s, that actually happened: Squads of men would enter people’s homes in the middle of the night, breaking down doors if necessary, to inject people with smallpox vaccines.