More than three years into the coronavirus pandemic and days from the May 11 end of the national public health emergency, a new subvariant is gaining ground in Maryland and across the country.

Exactly how many people have it and where, no one knows. Even in Maryland, where test results are still reported, real-time data is scarce.

The change reflects the new stage in the pandemic and the end to the public health emergency globally. It’s not unexpected, but public health experts say the drop in testing and other data collection charts an uncertain course for current and future public health threats.

“There is no doubt we are in a much better place since the pandemic started,” said Dr. William Moss, who was vaccinology lead for the recently shuttered Johns Hopkins Coronavirus Resource Center. “But I think there are pros and cons about changes to the way we collect and report data.”

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What data will still be collected, and what won’t?

The U.S. Centers for Disease Control and Prevention will no longer require states to report test results after the emergency ends. The same is true with vaccinations, further eroding information available to understand the scope of infections and guide public preparation, Moss said.

Hospitals will still have to report how many patients have the virus, but they are not testing everyone anymore. Meghan McClelland, the Maryland Hospital Association’s chief operating officer, said hospitals decide who to test but generally are testing when “a patient comes in exhibiting symptoms of COVID-19.″

The University of Maryland Medical System, with about dozen hospitals plus urgent care centers, is testing those with symptoms; those who go to rehab, behavioral health facilities or other congregate settings; people who are immunocompromised or otherwise vulnerable; and those who were recently exposed.

Michael Schwartzberg, a system spokesman, said the hospitals will rely on experienced epidemiologists and infection prevention practitioners to guide safety measures and responses.

“Fortunately, we have become quite nimble in our response to new variants and continue to maintain a state of readiness within our network of hospitals,” he said.

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Unlike in many states, Maryland’s Department of Health continues to report what tests are done, plus hospitalizations and deaths, though it is now reporting weekly instead of daily. It moved the information on April 28 to a new website, health.maryland.gov/COVID.

Gone is information about outbreaks in schools and assisted living facilities. The state vaccine locator was replaced with a federal locator. And the COVID alert system that notified people of exposures ends Tuesday.

“These changes reflect the new phase of COVID-19 that we are in today,” said Laura Herrera Scott, Maryland’s health secretary, in a statement when the website changes were announced April 27. “We will continue to actively monitor trends related to COVID-19 and offer robust information about COVID-19 on our new webpages.”

With the data it has, a health department map currently shows community levels at “low” across the state. A separate graph shows hospitalizations are at the lowest point since the early days of the pandemic — below 100.

How will we see a new wave of infections coming?

If there is a new wave of infections, we might not know immediately. It would become obvious when hospitalizations eventually begin to rise, for example, said Dr. Georges Benjamin, executive director of the American Public Health Association and a former Maryland health secretary.

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Wastewater samples collected by the CDC would be another indicator.

But the decrease in reliable real-time data makes it tough to warn people about when to wear a mask, get a booster or take other measures, Benjamin said.

“We need the community to know when there is an outbreak, and here is what we need to protect ourselves,” he said. “We don’t have that now, and that’s the challenge we have.”

Virus experts aren’t expecting anything like the pandemic peak in January 2022 when thousands were hospitalized in Maryland.

Moss said the odds of a dangerous mutation of the coronavirus now is low. And most healthy people are less likely to get severely sick from most new variants because they have some immunity from vaccines and infections, though they could still be infected.

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COVID-19 still threatens older people and those with compromised immune systems. About 100 Maryland and 8,100 people across the country are currently hospitalized. About 1,000 die weekly in the U.S.

So-called long COVID, the post-infection syndrome where people still have symptoms or develop new ones, also remains a concern.

What’s going on with this subvariant?

The new omicron subvariant, XBB.1.16, was first seen in March and now comprises about 12% of cases, according to the CDC. In the region that includes Maryland, it’s 15.3% of cases. It’s gaining on its cousin, XBB.1.5, first found in October.

The estimated prevalence comes from genomic sequencing of a dwindling number of COVID-19 tests.

It doesn’t appear more dangerous to Americans, but that is likely because of their immune levels from infections and shots, even if they haven’t had either recently, said Andrew Pekosz, a professor of immunology at the Johns Hopkins Bloomberg School of Public Health.

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Most people have had at least one vaccination, though only about 17% have had a recommended booster. The waning immunity makes people more susceptible to at least mild infection and ups the risk they infect their older, sicker relatives or people in the community.

“There is virus out there now, and it’s changing a little bit here and there,” Pekosz said. “It’s doing what we’d expect now based on what we’ve seen during the pandemic. People will get reinfected, but not everybody.”

What about tests and vaccines after the emergency ends?

Free tests won’t be guaranteed. In Maryland, residents may continue to get them from local health departments and libraries, through Medicaid and even from some private insurers who choose to cover the cost.

Home tests expire but the dates have been extended on most by the U.S. Food and Drug Administration. (Some experts say that if the control line still works, the test probably still works.)

Vaccines will remain free for everyone as long as federal supplies last and should be covered by insurance after the emergency ends. Same with treatments such as the antiviral Paxlovid. There could be some cost-sharing for treatments and vaccines, especially for people who get them out of their insurance networks.

To simplify guidance, the FDA authorized a second bivalent vaccine booster for those 65 and older and those immunocompromised, as well as a first booster for children, a first bivalent booster for adults, plus vaccines for those still unvaccinated.

The bivalent booster contains protections against the original omicron variant and the BA.4 and BA.5 subvariants, which have mostly disappeared. FDA officials say the vaccine is effective against the new omicron XBB subvariants.

A federal advisory panel will meet in June to discuss which variants should be included in another booster, when it should be given and to whom.

Experts such as Moss and Pekosz expect there to be a new formulation accounting for subvariants, plus a recommendation for boosters, perhaps annually like the one for the flu, at least for those most at risk.

What happens to all the COVID data collection infrastructure now?

Pekosz said there is a need for resources to continue studying this virus because, “It’s the end of the emergency but not the end of COVID.”

But he said a failure to maintain data collection infrastructure would be harmful, leaving the country to “reinvent the wheel” when there is a new public health threat.

He and other experts said the data infrastructure could also track other infectious diseases, including other respiratory illnesses such as flu and RSV. But also, if funded and maintained, it would serve as an early warning system for all serious future threats.

“My fear is there’s been a pattern we follow over and over again where there is a huge investment in public health and as soon as a pandemic or outbreak goes away, the interest and attention diverts to something else,” Moss said. “That’s the danger.”

meredith@thebaltimorebanner.com