Last fall, when RSV and flu came roaring back from a prolonged and erratic hiatus, and COVID was still killing thousands of Americans each week, many of the United States’ leading infectious-disease experts offered the nation a glimmer of hope. The overwhelm, they predicted, was probably temporary—viruses making up ground they’d lost during the worst of the pandemic. Next year would be better.
And so far, this year has been better. Some of the most prominent and best-tracked viruses, at least, are behaving less aberrantly than they did the previous autumn. Although neither RSV nor flu is shaping up to be particularly mild this year, says Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security, both appear to be behaving more within their normal bounds.
But infections are still nowhere near back to their pre-pandemic norm. They never will be again. Adding another disease—COVID—to winter’s repertoire has meant exactly that: adding another disease, and a pretty horrific one at that, to winter’s repertoire. “The probability that someone gets sick over the course of the winter is now increased,” Rivers told me, “because there is yet another germ to encounter.” The math is simple, even mind-numbingly obvious—a pathogenic n+1 that epidemiologists have seen coming since the pandemic’s earliest days. Now we’re living that reality, and its consequences. “What I’ve told family or friends is, ‘Odds are, people are going to get sick this year,’” Saskia Popescu, an epidemiologist at the University of Maryland School of Medicine, told me.
Even before the pandemic, winter was a dreaded slog—“the most challenging time for a hospital” in any given year, Popescu said. In typical years, flu hospitalizes an estimated 140,000 to 710,000 people in the United States alone; some years, RSV can add on some 200,000 more. “Our baseline has never been great,” Yvonne Maldonado, a pediatrician at Stanford, told me. “Tens of thousands of people die every year.” In “light” seasons, too, the pileup exacts a tax: In addition to weathering the influx of patients, health-care workers themselves fall sick, straining capacity as demand for care rises. And this time of year, on top of RSV, flu, and COVID, we also have to contend with a maelstrom of other airway viruses—among them, rhinoviruses, parainfluenza viruses, human metapneumovirus, and common-cold coronaviruses. (A small handful of bacteria can cause nasty respiratory illnesses too.) Illnesses not severe enough to land someone in the hospital could still leave them stuck at home for days or weeks on end, recovering or caring for sick kids—or shuffling back to work, still sick and probably contagious, because they can’t afford to take time off.
To toss any additional respiratory virus into that mess is burdensome; for that virus to be SARS-CoV-2 ups the ante all the more. “This is a more serious pathogen that is also more infectious,” Ajay Sethi, an epidemiologist at the University of Wisconsin at Madison, told me. This year, COVID-19 has so far killed some 80,000 Americans—a lighter toll than in the three years prior, but one that still dwarfs that of the worst flu seasons in the past decade. Globally, the only infectious killer that rivals it in annual-death count is tuberculosis. And last year, a CDC survey found that more than 3 percent of American adults were suffering from long COVID—millions of people in the United States alone.
[Read: Is COVID a common cold yet?]
With only a few years of data to go on, and COVID-data tracking now spotty at best, it’s hard to quantify just how much worse winters might be from now on. But experts told me they’re keeping an eye on some potentially concerning trends. We’re still rather early in the typical sickness season, but influenza-like illnesses, a catchall tracked by the CDC, have already been on an upward push for weeks. Rivers also pointed to CDC data that track trends in deaths caused by pneumonia, flu, and COVID-19. Even when SARS-CoV-2 has been at its most muted, Rivers said, more people have been dying—especially during the cooler months—than they were at the pre-pandemic baseline. The math of exposure is, again, simple: The more pathogens you encounter, the more likely you are to get sick.
A larger roster of microbes might also extend the portion of the year when people can expect to fall ill, Rivers told me. Before the pandemic, RSV and flu would usually start to bump up sometime in the fall, before peaking in the winter; if the past few years are any indication, COVID could now surge in the summer, shading into RSV’s autumn rise, before adding to flu’s winter burden, potentially dragging the misery out into spring. “Based on what I know right now, I am considering the season to be longer,” Rivers said.
With COVID still quite new, the exact specifics of respiratory-virus season will probably continue to change for a good while yet. The population, after all, is still racking up initial encounters with this new coronavirus, and with regularly administered vaccines. Bill Hanage, an epidemiologist at Harvard’s T. H. Chan School of Public Health, told me he suspects that, barring further gargantuan leaps in viral evolution, the disease will continue to slowly mellow out in severity as our collective defenses build; the virus may also pose less of a transmission risk as the period during which people are infectious contracts. But even if the dangers of COVID-19 are lilting toward an asymptote, experts still can’t say for sure where that asymptote might be relative to other diseases such as the flu—or how long it might take for the population to get there. And no matter how much this disease softens, it seems extraordinarily unlikely to ever disappear. For the foreseeable future, “pretty much all years going forward are going to be worse than what we’ve been used to before,” Hanage told me.
[Read: The next stage of COVID is starting now]
In one sense, this was always where we were going to end up. SARS-CoV-2 spread too quickly and too far to be quashed; it’s now here to stay. If the arithmetic of more pathogens is straightforward, our reaction to that addition could have been too: More disease risk means ratcheting up concern and response. But although a core contingent of Americans might still be more cautious than they were before the pandemic’s start—masking in public, testing before gathering, minding indoor air quality, avoiding others whenever they’re feeling sick—much of the country has readily returned to the pre-COVID mindset.
When I asked Hanage what precautions worthy of a respiratory disease with a death count roughly twice that of flu’s would look like, he rattled off a familiar list: better access to and uptake of vaccines and antivirals, with the vulnerable prioritized; improved surveillance systems to offer people at high risk a better sense of local-transmission trends; improved access to tests and paid sick leave. Without those changes, excess disease and death will continue, and “we’re saying we’re going to absorb that into our daily lives,” he said.
And that is what is happening. This year, for the first time, millions of Americans have access to three lifesaving respiratory-virus vaccines, against flu, COVID, and RSV. Uptake for all three remains sleepy and halting; even the flu shot, the most established, is not performing above its pre-pandemic baseline. “We get used to people getting sick every year,” Maldonado told me. “We get used to things we could probably fix.” The years since COVID arrived set a horrific precedent of death and disease; after that, this season of n+1 sickness might feel like a reprieve. But compare it with a pre-COVID world, and it looks objectively worse. We’re heading toward a new baseline, but it will still have quite a bit in common with the old one: We’re likely to accept it, and all of its horrors, as a matter of course.
