Marjorie Taylor Greene, a prominent Republican congresswoman and a staunch ally of Trump, suggested a return to “measles parties” for children. She criticized contemporary attitudes towards vaccination, stating, “Now, they demonize parents who refuse to vaccinate their kids.”
That’s called vaccination. At least, that was one of the original methods. You can use killed virus, weakened virus, a related virus that triggers the same immune response (for example, cowpox for smallpox), or a selected part of the virus that will trigger the immune response but is not capable of infecting you. The last is the most common method used now because the weakened-virus approach can go badly wrong.
That comment clearly is a joke that references that