For those seeking clarity, here’s what we know for sure. A second round of boosters will come with two cons: They’ll cause side effects such as fever and body aches, probably at about the same level as side effects from a first booster, and they’ll be expensive for uninsured Americans, thanks to the government’s rejecting billions in COVID spending this month. Beyond that, the risks are only theoretical. “There’s no good data in humans yet for SARS-CoV-2 that boosting too frequently is going to cause damage to the system,” John Wherry, an immunologist at the University of Pennsylvania, told me.

A couple of potential drawbacks can be ruled out right away. According to one idea, too many boosters could lead to something called “immune exhaustion,” in which a person’s relevant T cells, after trying to fight off an intruder for years on end, begin to wear down. They “become literally exhausted; they are no longer functional,” Akiko Iwasaki, an immunologist at Yale, told me. This can affect people with chronic infections such as HIV, or even tumors. But vaccines involve limited, not chronic, exposure to the coronavirus’s spike protein, and there’s no evidence that boosters spaced four months apart would exhaust anyone’s immune system, Iwasaki said—although “if you’re giving it every week, that’s a different story.”

Another virtually moot risk is one floated in the Times: that repeated exposure to a vaccine designed around the original SARS-CoV-2 virus could train a person’s immune system (through a process called imprinting) so narrowly that it won’t recognize new variants. Such an effect is theoretically possible, but not supported by evidence and not worth worrying about at this point, Marion Pepper, an immunologist at the University of Washington, told me.