The COVID-19 public health emergency ends May 11. What happens then?

“We’re going to have 50 different experiments in 50 different states,” he said. “Policymakers would be wise to look at that experience and see what we learn and look at remedies if we need them. And if they’re not needed, celebrate.”

Despite the uncertainty, it’s clear that ending the public health emergency after nearly three years will bring about a host of changes. Here’s a look at a few of them.

Since March 18, 2020, state Medicaid programs have been prohibited from removing anyone from their rolls, regardless of eligibility. That brought enrollment in MassHealth to a record 2.3 million people, the Globe has reported.

The program will resume checking eligibility — and unenrolling those who are no longer eligible — starting April 1 under a Congressional spending law.

“The big question is what happens to people who are going to be re-determined,” Epstein said.

The change does not apply to private insurance companies so residents who are not enrolled in Medicaid will retain their coverage.

“There’s going to be a split between those who have health insurance and those who don’t,” Callaghan said. “If you’re uninsured and you have COVID-19, your hospital bills, hypothetically, could get quite high. And that’s a real concern.”

Callaghan said treatment costs could rise, bringing insurance premiums with them. “In the long run, everyone’s likely to see higher health care costs than in the public health emergency,” he said.

Callaghan said Massachusetts residents may feel less of an impact than people in other states, thanks to the state’s Medicaid eligibility policies.

The Food and Drug Administration’s emergency-use authorization for COVID-19 nasal swaps and saliva tests will remain in place after the emergency ends, but insurers will no longer be required to cover the cost of at-home tests, which have been available for free for more than a year.

Massachusetts law requires health insurers to cover all medically necessary COVID-19 treatment without charging co-pays or deductibles, according to insurance spokespeople.

Amy McHugh, spokeswoman for Blue Cross Blue Shield of Massachusetts, told the Globe that COVID-19 vaccinations and Paxlovid — Pfizer’s antiviral pill that alleviates COVID-19 — must be covered by insurance.

It is not yet clear whether free or subsidized services will remain available to people without insurance.

Kathleen Carey, professor of health law, policy and management at Boston University, said she is concerned that higher costs could make some people less likely to test for COVID-19 if they feel sick.

“We’ll see more out-of-pocket costs for people who are insured, but they’ll still have access to treatment and to vaccines,” Carey said. “It will be more of a burden for” people without insurance.

Luckily, Carey said, Massachusetts has relatively few uninsured residents compared to other states.

The Boston Public Health Commission said it was “reviewing the Biden administration’s decision,” but did not offer specific details on the city’s plans.

“We look forward to continuing to work with our partners in health care and local community-based organizations to ensure that access to vital COVID-19 services remains intact for all who need them,” the commission said in a statement.

Ashish K. Jha, the White House’s COVID-19 response coordinator, wrote on Twitter that changes in the availability and cost of vaccines and Paxlovid will not take effect immediately.

“On May 12, you can still walk into a pharmacy and get your bivalent vaccine. For free,” Jha wrote in a Twitter thread on Wednesday. “On May 12, if you get COVID, you can still get your Paxlovid. For free ... None of that changes.”

Jha said the country will likely transition away from vaccines being distributed, and paid for, by the federal government during “the summer or early fall.”

Vaccines will remain free for those with health insurance — the majority of Americans — but said details on their availability for people without insurance will be released later.

“We are committed to ensuring that vaccines and treatments are accessible and not prohibitively expensive for uninsured Americans,” Jha wrote.

Pfizer and Moderna have said their COVID-19 vaccines will likely cost between $110 and $130 per dose when they hit the commercial market.

Without the public health emergency, Medicare patients must again spend at least three days in a hospital before the program will cover a nursing home stay, the Globe has reported. During the pandemic, patients have been able to move to a nursing home after even a brief visit to the emergency room.

Mary Moscato, president of Hebrew SeniorLife Health Care Services, has said that returning the three-day rule will likely lead to longer stays for patients and further crowding at hospitals.

Enhanced payments for COVID-19 patients and the ability to use alternative spaces for treatment could also be rolled back, the Globe has reported.

Carey said the three-month warning that the emergency is ending will be valuable to local hospitals, which already face staffing and supply shortages.

Insurance coverage for virtual mental health and addiction treatment has already been extended until at least the end of the year.

After that, patients will be required to see their provider in person at least once per year, Dr. Miriam Komaromy, medical director of Boston Medical Center’s Grayken Center for Addiction, has told the Globe.

Medicare will continue to pay for video and audio-based virtual treatment, according to the US Health Resources and Services Administration.

“There’s probably no good time for politicians to end this public health emergency,” Callaghan said.

He said COVID-19 does not appear to be going away any time soon, but an emergency order can not stay in effect indefinitely.

Callaghan said much of the country has already “forgotten the pandemic” and ending the emergency signifies that the federal government is shifting its perspective on COVID-19.

“The public takes some of its cues from elected leaders,” he said. “If elected leaders have publicly pronounced that this is no longer an emergency, it could shape the way that everyday Americans feel about what’s going on.”

Carey said she is concerned about the message that sends to the public.

“It doesn’t mean that the public health problem is going away, that’s not going to change,” she noted. “May 12 is going to be no different from May 11.”

Daniel Kool can be reached at daniel.kool@globe.com. Follow him @dekool01. Felice J. Freyer can be reached at felice.freyer@globe.com. Follow her @felicejfreyer.