(NewsNation) — Millions of people could lose their health care coverage beginning Friday with the expiration of a pandemic-era rule that kept their Medicaid enrollment intact.

The continuous Medicaid coverage requirement granted during the COVID-19 pandemic is set to expire Friday, making this the largest health coverage transition since the Affordable Care Act’s enrollment period.

Even some who remain eligible could fall through the cracks in the system, NewsNation’s partner The Hill reported. Others who are no longer eligible might qualify for other types of coverage, including subsidized health insurance on the Affordable Care Act marketplaces.

Those currently receiving Medicaid will need to reenroll as usual to keep their coverage. States are expected to send out notices before changes occur. In some cases, people might be required to fill out paperwork to prove their eligibility, NPR reported.

Experts who spoke to both NPR and NBC encouraged enrollees to make sure the personal information on file for their Medicaid coverage is up to date, including their current mailing address and income.

More information about eligibility and coverage alternatives is available at Healthcare.gov.

The massive undertaking stems from a coronavirus relief bill that was passed in 2020, granting states additional Medicaid funding. That funding came with the understanding that no one would be dropped from coverage while the public health emergency was in effect.

Then in December, Congress set the March 31 deadline for those Medicaid protections. Enhanced federal Medicaid matching funds are set to phase down through December 2023, according to the Kaiser Family Foundation, which estimated between 5.3 million and 14.2 million Medicaid enrollees could be dropped in the following months.