Flu Season and Covid-19 Are About to Collide. Now What?

Hospitals in the US are already stressed. Now, they must brace for a wave of flu patients needing more beds, lab tests, and ventilators.
medical supplies
Photograph: Getty Images

In parts of the United States, autumn is coming. The mornings have a coolness. The dogwood leaves show an edge of color. And outside pharmacies, the banners of fall are appearing: “Flu shots here.”

This year in particular, health authorities hope Americans will listen. The overlap of the influenza season and the coronavirus pandemic could overwhelm the health care system if people don’t take the vaccine and the incidence of flu is high. Planners are worried about renewed pressure on hospital beds and protective equipment, and less visible pressure on laboratories, which have to use the same machinery and supplies to analyze diagnostic tests for both Covid-19 and flu.

“Coronavirus and influenza are going to compete for the same ER space, the same hospital beds, the same ICU beds, the same ventilators, the same personal protective equipment, the same staff,” says Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security who also works in several Pennsylvania hospitals as an infectious disease and critical care physician. “It's going to be extremely difficult in terms of hospital surge planning and capacity.”

We tend to underestimate the flu in the US. (There’s no better proof of that than the social media contention that Covid is “just like the flu,” which discounts the seriousness of both.) In a normal year, flu kills up to 60,000 people in the US and can put more than 800,000 in the hospital, as several US Centers for Disease Control and Prevention researchers and director Robert Redfield wrote last month in The Journal of the American Medical Association. It’s routine, at the height of flu season, for emergency rooms to be so slammed that they refuse to accept ambulances and turn patients away. “This could be the worst fall, from a public health perspective, we've ever had,” Redfield warned recently in a video interview with WebMD.

To hold that off, more attention than in previous years is being paid to persuading Americans to take the flu shot, something that has never been popular: In an average year, fewer than half of US adults do. Governors are urging their residents to get vaccinated—last week the governor of Michigan received a flu shot during a press conference—and states and the CDC are investing millions to provide more shots than usual.

But getting the vaccine into arms and noses will be challenging, because many of the venues where shots are normally delivered—workplace campaigns, back-to-school fairs—can’t be held this year. Meanwhile, supply chain slowdowns that affected Covid-19 testing through the summer, holding up sampling swabs, transport media, and laboratory reagents, have never caught up and may stymie flu testing, too.

It could all add up to a dire flu season—which could arrive just as cooler weather and the resumption of in-person schooling force people inside, where shared air and surfaces make Covid-19 transmission more likely. People who work in hospitals are bracing for the results.

“People forget that even before Covid we always had a crunch during flu season,” says Helen Boucher, an infectious disease physician and head of several programs at Tufts Medical Center. “Our hospitals are not designed to have excess capacity—we run at 100 percent capacity every day.”

But what may lie in wait for hospitals this fall is not just a simple equation of: More flu cases + more Covid cases = more bodies lined up for hospital beds. People admitted with serious respiratory infections may have to be in those beds longer, because only a test result can distinguish one severe respiratory infection from another and indicate which treatment is appropriate. The steroids that soothe the inflammation of severe Covid-19 shouldn’t be given to flu patients, and the antivirals that improve flu if given immediately don’t affect the novel coronavirus.

Given testing delays, treatment decisions may take a while—and that could mean more days that a patient occupies a hospital bed, and possibly an intensification of illness that causes that patient to need a yet-more-scarce ICU bed instead. “Labs are already at or near capacity for testing of respiratory specimens, and it's going to be the same people, the same equipment, the same space, where flu testing will be conducted,” says Kelly Wroblewski, director of infectious disease programs at the Association of Public Health Laboratories.

Expanding testing capacity to make room for flu diagnosis isn’t just a matter of finding more swabs and tubes, or even personnel. It’s also a matter of the real-time PCR (polymerase chain reaction) readers the tests are performed on; that supply chain is equally under strain.

“Some of these instruments, especially the high-throughput ones, they're big, the size of a car. And they're expensive, a half-million dollars or more,” Wroblewski says. “There are not hundreds sitting in a warehouse ready to ship out. Right now, if a lab puts in an order, they're probably not going to get it until January, or February, more realistically.”

Because of the predicted hospital crunch, health authorities are leaning hard on getting people to take the flu shot. This is no simple task. Not only is acceptance of the shot low across the population—it was taken by 45 percent of adults in the 2018–19 season, according to that JAMA analysis, and only 37 percent the year before—but acceptance is even lower among racial and ethnic minorities. That low vaccination rate arises from a complex set of reasons: They include people having lower-paying jobs that don’t provide flu shot programs, people living in neighborhoods that lack accessible clinics, or people who distrust the US health care system’s treatment of minorities based on long-remembered scandals such as the Tuskegee syphilis study.

Whatever the reason, it leaves the same segments of the population vulnerable to the flu who have already suffered the highest rates of illness and death from Covid-19. That racial disparities exist with the patchwork of the pandemic is well-documented. The death rate among Black US residents is twice that of white residents, and rates of hospitalization among Black and Hispanic residents and American Indians and Alaska Natives can be as much as five times higher. Last month, the CDC found that a “high percentage” of cases that occurred in counties that were Covid-19 hot spots happened in communities of color. Flu would make that unfair burden worse.

“We need to focus, right now, on getting people vaccinated and reemphasizing masking, physical distancing, and handwashing,” says Georges Benjamin, a physician and the executive director of the American Public Health Association. “We’d like to take the influenza problem off the table.”

Getting better uptake in flu shots might accomplish several things. A flu vaccine won’t prevent Covid-19, of course, as they are caused by different viruses. But it will reduce the number of people coming into hospitals with illnesses that need to be sorted out, and it will cut back the occurrence of rare but serious cases in which someone comes down with both illnesses at once.

And the benefits of protection go both ways. Preventing flu might make the Covid pandemic more manageable, and preventing coronavirus transmission might reduce the occurrence of flu as well. “In South Africa this summer, flu cases went down, because of greater distancing and wearing of masks,” says Julia Swann, a professor of industrial and systems engineering at North Carolina State University, who consulted for the CDC during the 2009 H1N1 flu pandemic. “That is possible for us, if people can remain vigilant.” It’s also possible that might happen inadvertently, she added: If enough universities or cities have to go back into lockdown as Covid-19 spikes, the social distancing that follows could squelch the pandemic curve and the flu season at the same time.

One thing that the pandemic won’t affect is the availability of this year’s flu shot. Tinglong Dai, a professor of operations management and business analytics at the Johns Hopkins Carey Business School, points out that those doses have been packed for weeks and are already on their way to doctors and pharmacies. So frequently predicted shortages of glass vials and syringes won’t affect whether we can prevent flu this year.

But next year is another story. Experts in supply-chain management are already concerned that the enormous need for vials, syringes, and manufacturing capacity to produce millions or billions of coronavirus vaccine doses could disrupt packaging and delivery of the flu shots for 2021. Another possible shortage: personnel to check the work after manufacturing is complete.

“People think about the availability of machines but not to the need for human resources,” Dai says. “FDA will be deeply involved in the production and verification of the coronavirus vaccine. Quality assurance takes a lot of personnel. That could easily become a bottleneck.”

Even though we’re eight months into the pandemic now, the near-term behavior of the novel coronavirus is still uncertain: Viruses’ behaviors can change as they adapt to new hosts, and their sensitivity to seasonal change can be affected by indoor temperatures and ventilation as well as conditions outside. And flu season can last well into spring.

That is a long span over which to predict the interactions of two diseases that are insufficiently understood. There could be a bad flu season, or a mild one; a severe wave of Covid-19, or something no one has foreseen. Most of that is not under our control. But taking the flu shot is.

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