To Mr. Paul’s point: Natural immunity from the coronavirus is fortunately quite strong. A vast majority of people infected produce at least some antibodies and immune cells that can fight off the infection. And the evidence so far suggests that this protection will persist for years, preventing serious illness, if not reinfection.

But there is a “massive dynamic range” in that immune response, with a 200-fold difference in antibody levels.

In people who are only mildly ill, the immune protection that can prevent a second infection may wane within a few months. “Those people might benefit more from the vaccine than others would,” said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health.

The diversity in the immune response from natural infection might be because of differences in the amount of virus to which the person was exposed.