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Will Flu and RSV Always Be This Bad?

Will Flu and RSV Always Be This Bad?

In the Northern Hemisphere, this year’s winter hasn’t yet begun. But Melissa J. Sacco, a pediatric-intensive-care specialist at UVA Health, is already dreading the arrival of the one that could follow.

For months, the ICU where Sacco works has been overflowing with children amid an early-arriving surge of respiratory infections. Across the country, viruses such as RSV and flu, once brought to near-record lows by pandemic mitigations, have now returned in force, all while COVID-19 continues to churn and the health-care workforce remains threadbare. Most nights since September, Sacco told me, her ICU has been so packed that she’s had to turn kids away “or come up with creative ways to manage patients in emergency rooms or emergency departments,” where her colleagues are already overwhelmed and children more easily slip through the cracks. The team has no choice: There’s nowhere else for critically ill kids to go.

Similar stories have been pouring in from around the nation for weeks. I recently spoke with a physician in Connecticut who called this “by far the worst spike in illness I’ve seen in 20 years”; another in Maryland told me, “There have been days when there is not an ICU bed to be found anywhere in the mid-Atlantic.” About three-quarters of the country’s pediatric hospital beds are full; to accommodate overflow, some hospitals have set up tents outside their emergency department or contemplated calling in the National Guard. Last week, the Children’s Hospital Association and the American Academy of Pediatrics asked the Biden administration to declare a national emergency. And experts say there’s no end to the crisis in sight. When Sacco imagines a similar wave slamming her team again next fall, “I get that burning tear feeling in the back of my eyes,” she told me. “This is not sustainable.”

The experts I spoke with are mostly optimistic that these cataclysmic infection rates won’t become an autumn norm. But they also don’t yet fully understand the factors that have been driving this year’s surge, making it tough to know with certainty whether we’re due for an encore.

One way or another, COVID has certainly thrown the typical end-of-year schedule out of whack. Respiratory viruses typically pick up speed in late fall, peak in mid-to-late winter, and then bow out by the spring; they often run in relay, with one microbe surging a bit before another. This year, though, nearly every pathogen arrived early, cresting in overlapping waves. “Everything is happening at once,” says Kathryn Edwards, a pediatrician and vaccinologist at Vanderbilt University. November isn’t yet through, and RSV has already sent infant hospitalizations soaring past pre-pandemic norms. Flu-hospitalization rates are also at their worst in more than a decade; about 30 states, plus D.C. and Puerto Rico, are reporting high or very high levels of the virus weeks before it usually begins its countrywide climb. And the country’s late-summer surge in rhinovirus and enterovirus has yet to fully abate. “We just haven’t had a break,” says Asuncion Mejias, a pediatrician at Nationwide Children’s Hospital.

Previous pandemics have had similar knock-on effects. The H1N1-flu pandemic of 2009, for example, seems to have pushed back the start of the two RSV seasons that followed; seasonal flu also took a couple of years to settle back into its usual rhythms, Mejias told me. But that wonky timetable wasn’t permanent. If the viral calendar is even a little more regular next year, Mejias said, “that will make our lives easier.”

This year, flu and RSV have also exploited Americans’ higher-than-average vulnerability. Initial encounters with RSV in particular can be rough, especially in infants, whose airways are still tiny; the sickness tempers with age as the body develops and immunity builds, leaving most children well protected by toddlerhood. But this fall, the pool of undefended kids is larger than usual. Children born just before the pandemic, or during the phases of the crisis when mitigations aplenty were still in place, may be meeting influenza or RSV for the first time. And many of them were born to mothers who had themselves experienced fewer infections and thus passed fewer antibodies to their baby while pregnant or breastfeeding. Some of the consequences may already have unfurled elsewhere in the world: Australia’s most recent flu season hit kids hard and early, and Nicaragua’s wave at the start of 2022 infected children at rates “higher than what we saw during the 2009 pandemic,” says Aubree Gordon, an epidemiologist at the University of Michigan.

In the U.S., many hospitals are now admitting far more toddlers and older children for respiratory illnesses than they normally do, says Mari Nakamura, a pediatric-infectious-disease specialist at Boston Children’s Hospital. The problem is worsened by the fact that many adults and school-age kids avoided their usual brushes with flu and RSV while those viruses were in exile, making it easier for the pathogens to spread once crowds flocked back together. “I wouldn’t be surprised,” Gordon told me, “if we see 50 to 60 percent of kids get infected with flu this year”—double the estimated typical rate of 20 to 30 percent. Caregivers too are falling sick; when I called Edwards, I could hear her husband and grandson coughing in the background.

By next year, more people’s bodies should be clued back in to the season’s circulating strains, says Helen Chu, a physician and an epidemiologist at the University of Washington. Experts are also hopeful that the toolkit for fighting RSV will soon be much improved. Right now, there are no vaccines for the virus, and only one preventive drug is available in the U.S.: a tough-to-administer monoclonal antibody that’s available only to high-risk kids. But at least one RSV vaccine and another, less cumbersome antibody therapy (already being used in Europe) are expected to have the FDA’s green light by next fall.

Even with the addition of better tech, though, falls and winters may be grueling for many years to come. SARS-CoV-2 is here to stay, and it will likely compound the respiratory burden by infecting people on its own or raising the risk of co-infections that can worsen and prolong disease. Even nonoverlapping illnesses might cause issues if they manifest in rapid sequence: Very serious bouts of COVID, for instance, can batter the respiratory tract, making it easier for other microbes to colonize.

A few experts have begun to wonder if even milder tussles with SARS-CoV-2 might leave people more susceptible to other infections in the short or long term. Given the coronavirus’s widespread effects on the body, “we can’t be cavalier” about that possibility, says Flor Muñoz Rivas, a pediatrician at Baylor College of Medicine. Mejias and Octavio Ramilo, also at Nationwide, recently found that among a small group of infants, those with recent SARS-CoV-2 infections seemed to have a rougher go with a subsequent bout of RSV. The trend needs more study, though; it’s not clear which kids might be at higher risk, and Mejias doubts that the effect would last more than a few months.

Gordon points out that some people may actually benefit from the opposite scenario: A recent brush with SARS-CoV-2 could bolster the body’s immune defenses against a second respiratory invader for a few days or weeks. This phenomenon, called viral interference, wouldn’t halt an outbreak by itself, but it’s thought to be part of the reason waves of respiratory disease don’t usually spike simultaneously: The presence of one microbe can sometimes crowd others out. Some experts think last year’s record-breaking Omicron spike helped punt a would-be winter flu epidemic to the spring.

Even if all of these variables were better understood, the vagaries of viral evolution could introduce a plot twist. A new variant of SARS-CoV-2 may yet emerge; a novel strain of flu could cause a pandemic of its own. RSV, for its part, is not thought to be as quick to shape-shift, but the virus’s genetics are not well studied. Mejias and Ramilo’s data suggest that the arrival of a gnarly RSV strain in 2019 may have pushed local hospitalizations past their usual highs.

Behavioral and infrastructural factors could cloud the forecast as well. Health-care workers vacated their posts in droves during the pandemic, and many hospitals’ pediatric-bed capacity has shrunk, leaving supply grossly inadequate to address current demand. COVID-vaccination rates in little kids also remain abysmal, and many pediatricians are worried that anti-vaccine sentiment could stymie the delivery of other routine immunizations, including those against flu. Even temporary delays in vaccination can have an effect: Muñoz Rivas points out that the flu’s early arrival this year, ahead of when many people signed up for their shot, may now be aiding the virus’s spread. The new treatments and vaccines for RSV “could really, really help,” Nakamura told me, but “only if we use them.”

Next fall comes with few guarantees: The seasonal schedule may not rectify itself; viruses may not give us an evolutionary pass. Our immune system will likely be better-prepared to fend off flu, RSV, rhinovirus, enterovirus, and more—but that may not be enough on its own. What we can control, though, is how we choose to arm ourselves. The past few years proved that the world does know how to drive down rates of respiratory disease. “We had so little contagion during the time we were trying to keep COVID at bay,” Edwards told me. “Is there something to be learned?”