Senator Rand Paul, Republican of Kentucky and a former ophthalmologist, said he was “going with the science on this one” in refusing a vaccine.

“I have not chosen to be vaccinated because I got it naturally,” Mr. Paul, who tested positive for the virus last March, recently told reporters. (The science says the opposite; the Centers for Disease Control and Prevention recommends that people get vaccinated even if they have already had the coronavirus.)

“I had Covid,” said Senator Ron Johnson, Republican of Wisconsin. “I think that probably provides me the best immunity possible actually having the disease.”…

Some Democrats and Republicans have publicly and privately said they were uncomfortable about the optics of getting vaccinated before their constituents could, and would refrain from it until access was more widespread.