What happens after Omicron? Here’s what experts predict

The surge fueled by the Omicron variant will likely fade in the weeks ahead in the United States, experts say, and encouraging case declines have already emerged in Massachusetts and other states in the Northeast.

But what comes after that? Some experts are expecting a lull in the pandemic followed by a decline in the severity of future waves. But many also warn that it’s hard to predict where the pandemic will go next — and a new variant could throw everything into doubt.

“I want to emphasize that we don’t know what comes after Omicron,” said Dr. Jake Lemieux, an infectious disease specialist at Massachusetts General Hospital and co-leader of the viral variants program at the Massachusetts Consortium on Pathogen Readiness.

“I think we should be optimistic about where we are, because we have learned a lot about vaccines, we have new drugs that are available, and we have now public health tools that we know work well,” he said in a media briefing Tuesday. “But the pandemic has been incredibly humbling in that, you know, it’s impossible really to predict with certainty what is going to happen.”

One possible scenario is that the Omicron surge will subside and be followed by a pandemic hiatus of sorts, because of the large number of people who will have been infected, vaccinated, or both.

“I think we’re going to go through a pretty quiet period,” said Matthew Fox, a professor of epidemiology and global health at Boston University School of Public Health, with previous infections and vaccinations creating a “wall” against the virus. It’s the “most likely pattern,” he said.

“I think we will have a relative lull,” Michael Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, told STAT News this week.

Once it’s swept past, the Omicron surge could also make future pandemic waves less intense, some experts argue.

“By infecting large numbers of people quickly, [Omicron] is also generating immunity quickly. And that counts toward making Covid-19 a more manageable illness, since the layers of immunity may provide protection against future waves and variants,” William Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health and a co-director of its Center for Communicable Disease Dynamics, suggested Wednesday in a New York Times op-ed.

“No one should confidently assert that Omicron signals the end of the pandemic, but we should be confident that future surges of infections, whether with Omicron or whatever variant comes next, will make fewer of us seriously ill than they would have before,” he asserted.

Christopher Murray, director of the University of Washington Institute for Health Metrics and Evaluation, sounded an even more optimistic note Wednesday in a commentary in the journal The Lancet. “After the omicron wave, COVID-19 will return but the pandemic will not,” he said.

The future health impacts of the spread of the coronavirus “will be less because of broad previous exposure to the virus, regularly adapted vaccines to new antigens or variants, the advent of antivirals, and the knowledge that the vulnerable can protect themselves during future waves when needed by using high-quality masks and physical distancing,” he said.

“COVID-19 will become another recurrent disease that health systems and societies will have to manage,” he said.

But others aren’t quite as confident, worrying about the possible rise of a new variant that could circumvent existing immunity.

“The biggest threat would be the emergence of a new strain resistant to prior infection and vaccination,” said Fox.

Lemieux said, “I do think things will get better. But we’re going to have to keep a really close eye on the evolution of this virus because that has continued to be a major factor in the pandemic to date and I don’t expect that to change.”

Paul Bieniasz, head of the laboratory of retrovirology at Rockefeller University, said the optimistic outlook, which is “completely plausible,” is that the coronavirus will one day join other coronaviruses, such as those that cause the common cold, in causing only mild disease.

“But that is not inevitable. It’s not a given that that’s going to happen,” he said.

“What keeps me awake at night is thinking about what the properties of the next variant will be,” he said Thursday. “The notion of whether there will be another variant — that’s not in doubt. There will be. What is in doubt is what its properties will be and how effectively our immune systems will be able to deal with it.”

Some experts have even warned of the nightmare scenario of a new variant that would be just as transmissible as Omicron while at the same time causing disease as severe as the Delta variant that it replaced.

Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, warned Tuesday in a tweet that the immunity generated by Omicron might fade fast, opening the door to a variant as soon as this spring.

“There’s no consensus, but I feel that omicron will not produce long lasting or durable protection and we’ll be vulnerable to a new variant this spring/summer,” he said.

Experts say that as long as there are large groups of unvaccinated people worldwide, the virus can infect people, replicate, and continue to mutate, producing new variants. And they’ve called for using the post-Omicron window to vaccinate places that currently have little protection, such as Africa, where only a small fraction of people have gotten shots.

“The biggest thing we could do to minimize the likelihood” of another variant emerging is “to get vaccinations around the world,” Fox said. “That’s got to be a huge focus.”

“Vaccinating the world has always been important,” said John Moore, a virologist at Weill Cornell Medical College. “For the past two years, scientists have been warning that variants arise and cross borders.”

Moore emphasized that no one knows for sure what will happen next. “Who saw the Delta wave? Who saw the Omicron wave?” he said. “We don’t know what’s going to happen. ... Crystal ball-gazing by people in the scientific community doesn’t have a perfect record.”

Jeremiah Manion of the Globe staff contributed to this report.

Martin Finucane can be reached at martin.finucane@globe.com.