Flu practically vanished last year. Now doctors are bracing for potential ‘twindemic’ of flu and covid-19 spikes

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Health officials are urging Americans to get their flu shots, warning the flu season that didn’t materialize when most of society was shut down last year could come roaring back and strain hospitals in the months ahead.

Survey data released Thursday, Oct. 7, 2021, found slightly more than half of American adults plan to be vaccinated against influenza. That’s not much of a change from pre-pandemic surveys conducted by the National Foundation for Infectious Diseases, but health authorities are alarmed because some evidence points to a potentially more severe flu season. Experts say Americans have built up less natural immunity against influenza because so few were infected in 2020.

“This low flu activity was likely due to the widespread implementation of covid-19 preventive measures like masks, physical distancing and staying home,” Centers for Disease Control and Prevention Director Rochelle Walensky said in a Thursday briefing announcing flu vaccination efforts.

“Because of so little disease last year, population immunity is likely lower, putting us all at risk of increased disease this year,” she added.

The United States already saw a similar pattern with the spring and summer resurgence of common viruses including respiratory syncytial virus, known as RSV. Hospitals reported surprisingly high numbers of toddlers coming in with severe cases, likely because they were not exposed as infants in the early months of lockdown.

Flu viruses may also roar back with more opportunities to spread this fall and winter in reopened schools, workplaces and businesses, especially where masks are not mandated. Hospitals already battling simultaneous pediatric spikes in covid-19 and RSV fear oxygen and staffing will be stretched thin if flu and coronavirus admissions surge together in the months ahead – a dreaded scenario they avoided during the last winter surge.

The fears are especially acute after hospital systems, especially in the South, struggled to manage the summer wave of covid-19 admissions, said Nancy Foster, vice president for quality and patient safety policy at the American Hospital Association.

She noted some hospitals, including in Florida and California, were running out of oxygen because of the heavy demand from covid-19 patients struggling to breathe. Hospital leaders also fear burnout among doctors, nurses and respiratory therapists who have been on the front lines of the pandemic and have been growing frustrated as they confront coronavirus surges that robust vaccinations would have prevented.

“The same specialists who would care for covid patients are among those who would be caring for flu patients as well,” Foster said last week. “We don’t want those individuals to be so overworked they cannot appropriately care for you, regardless of what brought you into the hospital.”

The Cedars-Sinai health-care system in Southern California, which battled a devastating coronavirus surge in the winter but had zero flu cases, is among the hospitals urging people to get coronavirus vaccinations and flu shots to prevent spikes of both.

“It would be worst-case scenario,” said Soniya Gandhi, an infectious-disease physician and vice president for medical affairs. “There are several hospitals operating at full capacity. And that’s now. So going into the winter, the best way to protect and preserve that hospital capacity is for individuals to be vaccinated as much as possible.”

Flu seasons are notoriously difficult to predict. While experts agree another nonexistent season is unlikely, other evidence suggests the upcoming one could be typical or milder than normal.

Some experts say the remnants of coronavirus-containing measures, from school mask mandates to office reopenings delayed until next year, could block the virus from circulating as it would in a normal year.

The public may have also learned some good infectious-disease practices after more than 18 months of pandemic life. The National Foundation for Infectious Diseases survey found that nearly half of respondents were more likely to stay home when sick because of the pandemic and slightly more would wear masks in some crowded situations.

The survey was also conducted in early August before the late summer surge in coronavirus cases brought more attention to the pandemic’s continued dangers and before public health authorities could launch an extensive flu vaccine drive.

“None of us can predict whether it will be mild, moderate or severe flu season, but we are certain that there will be flu activity,” said William Schaffner, medical director of the National Foundation for Infectious Diseases. “We certainly don’t want a twindemic, both covid and influenza.”

Public health authorities are worried that parents may let their guard down about the flu. While one child died in the 2020-21 flu season, nearly 200 did the year before.

Walensky cited new estimates showing that about 59 percent of children ages 6 months to 17 years received a flu shot the past season, a slight decline from the previous season. She attributed the decrease to disruptions in routine medical care during the pandemic.

Regulators could authorize the Pfizer-BioNTech coronavirus vaccine for children between the ages of 5 and 12 as soon as November, paving the way for some children to receive flu and coronavirus shots at the same time. Doctors are urging parents to bring their children in for flu shots earlier with flu season already starting in much of the country.

Brandi Freeman, a pediatrician at the University of Colorado School of Medicine, said parents have already been pushing for flu shots since August, although the first shipment didn’t arrive until this month.

The demand is welcome news to a pediatrician emerging from an unusually busy summer and not expecting much of a break with schools back in session and kids becoming exposed to viruses for the first time.

“We are trying to restructure our clinic, restructure our staffing to be able to accommodate what we expect to be a pretty intense season,” Freeman said.

She’s also told parents to expect doctors to be overwhelmed trying to figure out which respiratory virus is making which child sick, especially if multiple infections spike at once. The more viruses a child has been vaccinated against, the easier that detective work becomes.

The Children’s Hospital of Atlanta, one of many hospitals throughout the Southeast reporting a spike in pediatric RSV cases over the summer, is preparing for the possibility of a similar surge in pediatric flu cases after the Thanksgiving and Christmas holidays.

“One of the challenges we face is because we thankfully did not have a very active flu season last year, some parents feel flu is not a concern,” said Andi Shane, the hospital’s medical director of infectious disease. “I think it’s important we understand what happened last year was great in the sense we didn’t have a lot of transmission . . . but we may have less immunity.”