No one knows what kind of flu season is coming to the Cincinnati region and the nation.
The usual guesswork abounds because no two seasons are alike, and last year was like no other.
Now some French researchers suggest that we may now face an “immunity debt.”
In the second autumn of the coronavirus pandemic, experts say the only certainty is the refrain of prevention: hand-washing, staying home when sick, masking and getting vaccinated against the seasonal influenza virus.
“We say, if you’ve seen one flu season, you’ve seen one flu season,” said Dr. Josh Schaffzin, director of infection prevention and control at Cincinnati Children’s Hospital Medical Center.
“It will be a challenge if it’s a severe season, no question. But no matter what, there will be a flu season, and we should prepare as we always have for that.”
Last winter, flu flat-lined in the Cincinnati region and the nation as people took the stepped-up precautions against the new coronavirus, and tamped down flu.
In Ohio, only 122 people were hospitalized for flu between September 2020 and May. The previous season, flu put 11,065 Ohioans in hospitals.
About 125 children on average die from flu every year in the United States. Last year, the nation counted one pediatric death.
Contributing to the ebb of flu last year were the 193.8 million vaccinations were given, an 11% increase over 2019-20, and a 28% increase over 2010-11, the most recent year in which flu was pandemic.
Everyone 6 months and older needs a flu shot, according to the U.S. Centers for Disease Control and Prevention. But getting people to get flu shots has always been a challenge.
In 2019-20, the most recent year of CDC data, only 51.8% of the U.S. population took flu vaccination, an increase of 2.6% over the previous year.
CVS pharmacies delivered more than twice the usual number of flu shots in 2020-21, and with Walgreen started delivering inoculations for this season in mid-August.
“We are concerned that as many of our patients as possible get vaccinated for flu,” said Jennifer Rudell, Cincinnati district leader for CVS Health and a pharmacist.
She said a customer can get a flu shot and a COVID-19 vaccination at the same time.
Rudell and other experts said flu shots are especially critical now, as mask restrictions have eased since a year ago, even as the more infectious delta variant of the coronavirus hospitalizes almost as many people as during the winter spike.
One possible indicator is ahead of schedule at Cincinnati Children’s. Respiratory syncytial virus is a common cold-like infection in children, and Schaffzin said the hospital is seeing an RSV caseload that would usually turn up in December.
“It’s making us very busy on top of being busy at baseline,” he said.
Dr. Stephen Feagins, medical director of Hamilton County Public Health and chief clinical officer for Bon Secours Mercy Health-Cincinnati, said the early tide of RSV could be a directional signal for flu.
He noted research from France this summer about a phenomenon called “immunity debt.”
The paper published this month in the journal Infectious Diseases Now suggests that when children are not exposed to a pathogen because of pandemic restrictions, immunity wanes since it has nothing to fight. When restrictions lift, and the pathogen returns, the immunity debt gets paid with more people getting sicker, sooner.
“Mathematical models suggest that respiratory syncytial virus and possibly influenza epidemics may be more intense in the coming years,” the paper says.
“The typical age for a child to develop respiratory syncytial virus is 17 months,” Feagins said, “and what we’re seeing now is that they’re getting it about 6 months because the mothers during pregnancy weren’t exposed to RSV and so did not provide the antibodies to their babies.”
Schaffzin said he finds the “immunity debt” concept plausible, but still a theory, and verification will only come after flu season or even several seasons.
“We’ll know what we know when we know it. The prevention message has not changed at all. Respiratory viruses you can prevent with good hand hygiene then masking on top of that,” he said.
The pandemic made a believer out of Schaffzin in the value of face masks.
“Before COVID, I was skeptical of the efficacy of masking. At the time, the data were not convincing,” he said.
“And I was wrong. I was totally wrong.”
“The data have changed my mind,” he said, “and have shown us there is something to this low-cost straightforward intervention that we need to consider.”