The vaccines are supposed to be free. Surprise bills could happen anyway.

“What makes the vaccine protections unique is that there are requirements on both the insurers and the providers,” said Karyn Schwartz, a senior fellow at the Kaiser Family Foundation. “It’s a belt-and-suspenders approach that makes the consumer protections much stronger.”

Even with these protections, experts do see some weak spots. One has to do with the type of health coverage Americans carry. Millions are still covered by “grandfathered” health insurance plans, which existed before the Affordable Care Act and are exempt from its rules. So those plans are not required to fully cover the coronavirus vaccine, or any other preventive service.

Experts also worry about uninsured Americans. The United States does not have a national program to cover vaccination costs for them. For coronavirus, it is instructing health providers to submit costs associated with vaccination to a $175 billion Provider Relief Fund created last spring.

The fund had $30 billion remaining as of Nov. 10. There’s no backup source of funding for the uninsured to get covered if it’s depleted.