The first of the White House’s major initiatives to get everyone access to free, at-home COVID testing takes effect Saturday. Starting Jan. 15, private health insurers will be required to reimburse members for up to eight test kits per month.

But the new policy doesn’t benefit every American.

For starters, it only applies to people who have private health insurance. That leaves out uninsured people, an estimated 28 million or 8.6% of Americans.

It also doesn’t affect an even larger segment of the population: Americans 65 and older covered by Medicare. That’s 18.4% of Americans, as estimated by the U.S. Census Bureau in 2020.

Not everyone who has public health coverage is left out. Medicaid recipients and children covered by CHIP (Children’s Health Insurance Program) will be eligible for reimbursement.

“People with Medicaid or CHIP coverage should contact their state Medicaid or CHIP agency for information regarding the specifics of coverage for at-home COVID-19 tests, as coverage rules may vary by state,” says the Centers for Medicare and Medicaid Services.

Medicare recipients and uninsured Americans will still benefit from the White House’s plan to distribute 1 billion at-home COVID-19 tests directly to people for free. That plan is still in the works. People will soon be able to sign up to get a test mailed to them, the White House says, but the website to sign up hasn’t yet been launched.

More details and a website are expected to come next week.