Based on the quick rise and precipitous drop of Omicron in South Africa, Harvard experts are cautiously hopeful about a possible decline of the surging COVID variant in the very near future, even as they warn of dramatic case spikes, overloaded hospitals, and slowly rising deaths in the interim.

“In South Africa, the Omicron wave lasted on the order of weeks. I would imagine that this will be something that lasts similarly long, perhaps a bit longer in the U.S.,” said Jake Lemieux, an infectious diseases specialist at Massachusetts General Hospital, instructor in medicine at Harvard Medical School, and co-lead of the viral variants program at Massachusetts Consortium on Pathogen Readiness. “There’s a seasonal component to it — there was last season — so I think it’s going to be a difficult winter, and the maximal period seems like it’s about to unfold over the next few weeks.”

Lemieux and other coronavirus experts at MassCPR emphasized during a media call on Tuesday that important key questions remain unanswered and that the experience in South Africa — whose population is much younger than that of the U.S. — may not be mirrored here. Omicron peaked there weeks ago, followed by a rapid drop in cases, and the country has also seen proportionally lower levels of both hospitalizations and deaths.

“It’s very clear that there’s an astonishing number of cases, a moderate number of hospitalizations, and very low deaths,” said Dan Barouch, William Bosworth Castle Professor of Medicine at Harvard Medical School, director of Beth Israel Deaconess Medical Center’s Center for Virology and Vaccine Research, and co-lead of MassCPR’s vaccine research group.

Barouch also said that there is initial evidence in animal studies that the fast-spreading variant does indeed cause less severe disease, with infection concentrated in the upper airways and to a lesser extent in the lungs, where it can cause life-threatening pneumonia. “There is some emerging data in animal models … that infection of those animal models appears to result in robust upper-airway disease but less robust lower-airway disease and less severe pneumonias. That is certainly consistent with what we’re seeing clinically.”

Reports from the U.K., whose population more closely resembles the U.S. in age, indicate that cases have begun falling in London, though experts there questioned whether they might still plateau and warned that most of the decline has come in younger age groups.

The U.S. has seen no sign of an Omicron peak, however. Statistics from the Centers from Disease Control and Prevention show the seven-day moving average of new cases topping 491,000 on Jan. 3, nearly double last January’s pandemic peak of about 250,000. New daily hospital admissions, which typically trail cases by a few weeks, have risen as well, though, at 4.45 per 100,000 and have not yet topped last January’s Alpha variant-driven peak of 4.92.

Deaths, which trail hospitalizations, have surged since late November, but the seven-day average of 1,165 on Jan. 3 has not yet reached the levels seen during prior waves, including 2,299 during April 2020, when the original virus circulated, 3,421 in last January’s surge after Alpha had arrived on the scene, and 1,923 during this past September’s Delta wave.

Another result of Omicron’s rapid emergence in the U.S. has been rising numbers of children with COVID infections — 325,000 during the week ending Dec. 30 — though Katherine Luzuriaga, a pediatrician and vice provost for clinical and translational research at the University of Massachusetts Medical School, said they’re not seeing a significant increase in the rates of hospitalization or death due to the ailment.

“We’ve seen a huge surge in the number of children-reported cases of COVID infection,” Luzuriaga said, adding that some of those positives have come in youngsters admitted to hospitals for other conditions but tested for COVID. “Fortunately, to date we have not seen an increase in the rate of hospitalization due to COVID or in severity of disease due to COVID, and most of the severe cases that we are seeing in hospitals have primarily been in unvaccinated or under-vaccinated individuals.”

Despite those encouraging signs, the outlook for the immediate future remains perilous, with hospitals already operating at capacity and a recent survey of viral particles in Boston-area wastewater showing a massive spike in virus that so outstrips any point of the pandemic that Jeremy Luban, co-lead of MassCPR’s viral variants program, called it “absolutely terrifying.”

“We are, it is probably fair to say, engulfed in an Omicron wave right now, and the question is: How high does this wave go, and how severe is its impact going to be on patients, the health care system, and society?” said Lemieux. “We’re going to find out.”

Experts also pointed out that the U.S.’ size means it is likely that Omicron will play out — as did waves of other variants — at different times and in different manners in different parts of the country.

“The bottom line is that Omicron is going to visit every city and every town in the country and make its presence known,” said Luban, who is also a professor of molecular medicine, biochemistry, and molecular pharmacology at UMass Medical School. “I don’t think there’s any question about that.”

Though difficult weeks lie ahead, Barouch said that successive waves of infection and vaccination are shifting the landscape onto which new variants emerge to one where many potential hosts have some form of pre-existing immunity and some, having been vaccinated and infected, have several.

“I don’t think it’s a foregone conclusion that the next variant will necessarily be less pathogenic. That remains to be seen,” Barouch said about the odds of a new, less transmittable version. “But I do think that with each month that goes by, each variant that comes and goes, and each vaccine campaign, that we’re seeing a larger fraction of the U.S. population and also the global population with some level of immunity.”

Chicago’s public school system closed this week when the teachers’ union and the city clashed over in-person learning amid a spike in Omicron cases. The Gazette sought reaction from public health expert Joe Allen, an associate professor at the Harvard Chan School and director of the Healthy Buildings program, who believes the downsides of keeping children out of schools far outweigh the risks posed by COVID-19. The interview has been edited for clarity and length.

Q&A

Joe Allen

GAZETTE: Is it safe to sends kids back to school?

ALLEN: The argument for in-person schooling rests on to two pieces of evidence that we’ve had for a long time now: the risk to kids from this virus is low, and the costs of them being out of school is extraordinarily high. I want to be clear that by starting with kids, I’m not minimizing the adults in the school, teachers and staff. But this is not March 2020. We know a lot more; we have new tools at our disposal. The evidence on the low risk to kids has been consistent through each variant and each wave. The hospitalization rate has hovered at less than one per 100,000 through the Alpha wave, the Delta wave, and even the Omicron wave, and that’s important context because that level of risk is something we accept all the time.

The two most salient risk factors for this virus are age and vaccination status. And fortunately, kids have been low risk. If that doesn’t feel low risk enough, a safe and effective vaccine is available for all school-aged kids. It’s the same for adults ­— this vaccine is safe and effective. And even with Omicron and the higher risk of breakthrough infection, the protection against severe disease and death has stayed strong.

GAZETTE: What are the negative effects of not having kids in school?

ALLEN: The effects we’re seeing right now were predicted two years ago. We could start with learning loss. We see that students are four or five months behind in reading and math. We see even greater loss for Black or Hispanic students. And that’s the kids who were in school. Millions of kids are not — are missing from the system. Schools are the first place where we detect issues at home such as abuse, neglect, and maltreatment. And the idea that these short-term closures don’t have an impact is nonsense. In New York City, in just a few months there were thousands of cases of expected reports of child maltreatment that did not come in. I’ve written about the impacts on nutrition and kids, and food security, with Sara Bleich from the School of Public Health. We see the impact extend to women, working women in particular, who proportionately have the burden of childcare and homeschooling. So when we think about schools and risk, we can’t just think about the risk in the classroom, we have to think about what happens when you send these kids home. And I think there’s been a faulty assumption that if you close schools, that that protects everyone who would be at school. But that ignores the fact that social networks exist outside of school for kids and for adults, too. And we saw this when the winter break happened. Kids were not in school, teachers were not in school, and when they came back, even before they even entered school, some of the surveillance testing we’ve seen showed one-third of people were positive.

GAZETTE: Are teachers right to fear in-class teaching?

ALLEN: We need to reassure people that if you are vaccinated and boosted, you’re well protected. In addition, we’ve had the know-how, the guidance, and the money to put in effective controls in our schools for 18 months. From my understanding, they’ve done ventilation filtration upgrades in Chicago, they’re monitoring air quality in real time, they have vaccine clinics.

There has been this casualness about closing schools that I just don’t understand. When you match up the long list of harms when kids are out of schools against this idea that we’re just going to close for two days or a week or two weeks, which might turn into three weeks, who knows? I think that’s a mistake, and it ignores what we’ve learned over the past two years and all the new tools we have. Schools should not close.

GAZETTE: What are the best protections?

ALLEN: There’s been so much confusion over the past five months: Do vaccines work? What about a breakthrough case? Do those who are vaccinated transmit the same? What is the viral load? The higher order message that vaccines work got lost. You see it in the data everywhere. And we’ve seen it in the data since vaccines first came out. Vaccinated people are well protected from the most severe outcomes. Do breakthroughs happen that end up in hospitalizations? Yes. But they’re much less likely to occur for people who are vaccinated, and we’ve lost that message. I think that has fed into some of the concern around schools. It’s understandable that people are anxious, but they should be reassured that if they are vaccinated and boosted and again wearing a high-grade mask, then that’s excellent protection. So, the transmission is real, the breakthroughs are real. But I’m hoping that what people are starting to see, not just in the epidemiological data or the clinical data, but even their own personal anecdotal data, is that friends and relatives who are vaccinated and get this recover.

GAZETTE: What do you think about the test-to-stay approach that the CDC is has advised in order to help schools avoid online learning?

ALLEN: I fully support it. Quarantining is a blunt instrument that we used in the beginning of the pandemic when we didn’t know who was infectious. Now we can actually test to know who is infectious with good reliability, so you can keep kids in the classroom who may be in close contact with someone who has been infected but they aren’t infectious themselves. I also support test to return, which decreases the isolation period after you are infectious, and when you test negative you can come back. The challenge that the CDC has is that there’s just not enough testing around right now.