What group is especially vulnerable to the ravages of COVID-19 even if fully vaccinated and boosted? Seniors. And who will have an especially tough time getting free at-home COVID tests under the Biden administration’s plan? Yes, seniors.

As of Jan. 15, private insurers are covering the cost of eight at-home rapid COVID tests each month for their members — for as long as the public health emergency lasts.

Finding the tests will be hard enough, but Medicare beneficiaries face an even bigger hurdle: The administration’s new rule doesn’t apply to them.

It turns out that the laws governing traditional Medicare don’t provide for coverage of self-administered diagnostic tests, which is precisely what the rapid antigen tests are and why they are an important tool for containing the pandemic.

“While at this time original Medicare cannot pay for at-home tests, testing remains a critical tool to help mitigate the spread of COVID,” a statement from the federal Centers for Medicare & Medicaid Services said.

Medicare patients are left to seek free tests other ways, including through the administration’s new website, covidtests.gov, and at community centers. The Medicare program does cover rapid antigen or PCR testing done by a lab without charging beneficiaries, but there’s a hitch: It’s limited to one test per year unless someone has a doctor’s order.

More needs to be done, advocates say.

“We know that the Medicare program has significant flexibility relative to the public health emergency, and it has demonstrated it has the ability to alter the rules,” said David Lipschutz, associate director and senior policy attorney at the Center for Medicare Advocacy.

Why can’t the Medicare program reimburse beneficiaries for the over-the-counter tests or pick up the tab at the pharmacy as commercial health plans will do?

The services the Medicare program pays for are spelled out in federal law.

“It generally excludes over-the-counter things,” said Casey Schwarz, senior counsel for education and federal policy at the Medicare Rights Center, an advocacy group.

Some lawmakers in Congress are urging the administration to cover the tests.

“Demanding Medicare recipients — nearly one-fifth the population of the United States — to foot the bill out-of-pocket for at-home tests is unfair, inefficient, and will cost lives,” said Rep. Bill Pascrell Jr., D-N.J., who has urged the Biden administration to expand Medicare coverage to include them.

It may not be a simple change, as these tests appear to fall into coverage gaps. Medicare Part A covers hospitalization, and Part B generally covers provider-based services like doctor visits and lab tests. Part D covers drugs.

“So there’s a little bit of a question of where this type of benefit would fit,” Schwarz said.

So how can a Medicare beneficiary get free at-home COVID tests?

There are a couple of options. The Biden administration has launched a website, covidtests.gov, where anyone, including Medicare beneficiaries, can order free at-home COVID tests. Each residence initially can receive four tests.

What other free COVID-19 testing options are available to Medicare beneficiaries?

In traditional Medicare, beneficiaries can get rapid antigen or PCR diagnostic tests without paying anything out-of-pocket if the test is ordered by a doctor or other health care provider and performed by a lab.

The federal government has set up more than 10,000 free pharmacy testing sites across the country that Medicare beneficiaries can visit as well.