The pandemic’s much-discussed summer respite never came.
Instead, the U.S. has found itself with COVID-19 cases surging around the country into July, foreshadowing a potentially deadly duo in the fall: continued COVID-19 outbreaks combined with the seasonal flu.
“If COVID-19 and influenza peak at the same time this year, it could be quite disastrous,” Dr. Dan Uslan, co-chief infection prevention officer at UCLA Health, told TPM.
Doctors and health officials painted a complex and stark picture to TPM. The symptoms of influenza and COVID-19 are strikingly similar, making it difficult for hospitals to quickly diagnose and isolate contagious patients.
Once the flu season begins, “we will start from a higher level of COVID infection,” Dr. Ali Mokdad of the Institute for Health Metrics and Evaluation told TPM. “The second wave, or the first wave as it keeps continuing, is gonna come at the same time as the flu season, pneumonia season, which also have a big impact.”
The current high level of COVID-19 cases suggests that without massive further interventions, both diseases could end up intersecting in the U.S. at the same time — a fate that the country narrowly avoided as the pandemic began in earnest in March, just as the 2019-2020 flu season came to an end.
Different Illnesses, Similar Symptoms
The possibility that the U.S. could be hit by simultaneous waves of flu and COVID-19 presents a confounding problem: the symptoms look almost exactly alike. Both respiratory illnesses frequently present with fever, a deep cough, and trouble breathing in serious cases.
Difficulty in distinguishing between the illnesses could complicate detection — and patients’ decisions on when to seek hospital care, Adriane Casalotti, head of government relations for the National Association of County Health Officials, told TPM.
“People are scared of coronavirus — they recognize that it’s a significant illness, that people are dying of it, have died of it,” Casalotti said.
Dr. Paul Biddinger, director of emergency preparedness for Mass General Hospital and head of the emergency preparedness program at Harvard’s T.H. Chan School of public health, told TPM that “it’s basically impossible to tell the difference between COVID and flu without a test.”
He cast the problem as one of managing finite resources in an emergency. For hospitals seeking both to treat as many patients as possible and prevent the spread of both the flu and COVID-19 within their walls, having an onslaught of patients with both illnesses could throw a wrench in how quickly doctors can diagnose a patient and assign them to a bed for treatment.
Biddinger said that hospitals would likely have to prepare to test for both the flu and COVID-19.
“The problem is once you’re testing both, you have to rule out both from an infection control perspective, and it slows down the bed placement process,” he said.
Sarah Cobey, lead investigator at the University of Chicago’s Cobey lab which studies the interplay between immunity and pathogens with an eye towards epidemiological forecasting and vaccine design, has been focusing on the disparate testing issue.
She told TPM that she and officials at the National Institutes of Health have been discussing how to streamline the testing process with a dual flu-COVID-19 test.
The talks, she said, are “about trying to use COVID as a way to expand testing for the flu.”
“It would be amazing if, when people show up with respiratory symptoms, we could test them not just for flu but a whole panel of things,” she said. “But I feel like that would require remaking the health-care system. Insurance totally dictates which kinds of tests are supported — it’s unfortunate.”
She added that she’s hoping to set up or expand at least a few testing sites equipped with vigilant surveillance systems to try out testing for a slate of respiratory diseases at once.
Are Hospitals Prepared?
There’s no easy way to quantify the impact a flu season will have on hospital capacity.
The flu changes every year in its severity, depending in part on subtle shifts in how the virus mutates, and on the success of mitigation strategies like annual vaccination campaigns.
And some vaccines, Cobey said, just end up working better than others.
That presents a challenge to ascertaining how hard the U.S. will be hit this year when the temperature drops.
“We’re not at a point where we can predict far in advance which flu virus will dominate,” she said.
An additional problem, Cobey said, is that research suggests that getting the flu vaccine too early could actually weaken its effectiveness.
“Some research is suggesting that if you get the vaccine too long before flu season starts, the vaccine won’t protect you as much,” she said. “The antibodies wane.”
That could be a critical factor in combating the two-pronged wave of disease. “If we have a really bad flu season, that will increase the severity of the COVID-19 season and the health-care system will be strained,” she added.
Uslan said that the strain will trickle down to specific equipment, given that the diseases both target the respiratory system.
“Because both infections are quite similar, they use many of the same resources (ICU beds, ventilators, etc),” he said. “Since flu season on its own is a challenge to manage, having both infections peak around the same time will cause tremendous stress to our health-care system.”
As it is, the flu alone already strains hospitals across the country.
It’s common for the seasonal flu to fill up hospital ICUs. In the 2017-2018 flu season — the worst in the past decade — the CDC estimated that the total number of people hospitalized throughout the season was higher than the number of staffed hospital beds which existed in the U.S. at that time.
Around 959,000 people were hospitalized that season, while there were 902,202 staffed beds.
But to Biddinger, of Mass General, the problem looked to be one of sorting out which patient should go where.
If hospitals can’t quickly identify who is infected with what and, therefore, which bed to put the patient in, emergency rooms could begin to get backed up.
“Any excess above what your normal Emergency Department wait time is is really a problem,” Biddinger said. “Any excess results in very significant backloads in your Emergency Department”
Mitigation Efforts As The Silver Lining
Despite the fear and uncertainty of the coming cold season, there is a bright side to the parallel illnesses: COVID-19 mitigation strategies also help tamp down the spread of flu.
“The same preventive measures that work for COVID-19 (physical distancing, handwashing, etc) also help to prevent influenza, so it’s critically important to continue those measures as well,” Uslan, of UCLA Health, said.
Cobey told TPM that there is promising evidence from Hong Kong, where there was an abrupt drop in flu infections when people started taking COVID-19 precautions. There, COVID-19 hit earlier in the winter while flu season was still in full swing, a problem avoided in the United States the first time around.
“I wouldn’t be surprised if the severity of seasons and epidemics track to each other a little bit,” she said.