Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West

by Stephen E. Ambrose

on May 1, 1795, Lewis joined the regular army, with the rank of ensign. That same month, he was vaccinated for smallpox.

I don't imagine he had to contend with the same type of anti-vax MAGA political bullshit that we did re: Covid.