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This award-winning blog supplements the articles in Hospital Infection Control & Prevention.

Storm Watch: Severe Flu Season Ahead?

By Gary Evans, Medical Writer

A possible severe influenza season is on the horizon, in part because COVID-19 shutdowns and precautions led to a historically low flu season in 2019-2020, said Rochelle Walensky, MD, director of the Centers for Disease Control and Prevention (CDC).

“We had so little disease last year, population immunity will be lower, putting us all at increased risk for influenza this year, especially among those most vulnerable,” she explained at an Oct. 12, 2021, flu press conference held by the National Foundation for Infectious Diseases (NFID).

“When there is active flu one year to another, then we have more people — not just who are vaccinated — but people who were actually sick and have built up some protective immunity,” Walensky said. “That immunity actually helps us, especially those who have not been vaccinated. If they had the flu last year, they may have had some residual immunity against getting the flu this year.”

Although the SARS-COV-2 pandemic has dipped somewhat in the last month, there remain concerns about another surge of the Delta variant this winter as more people gather indoors and so many of them remain unvaccinated.

“We need to get that curve to go much further down than it is because we’re dealing with a situation where you have a highly transmissible virus and where the dynamics of the virus are at 80- to 90,000 cases a day," Anthony Fauci, MD, said at a White House Briefing on October 13. "That’s not where you want to be. ... About 66 million people who are eligible to be vaccinated remain unvaccinated."

Another predictor of more circulating influenza virus in the 2021-2022 season is the early, unseasonal appearance of respiratory syncytial virus (RSV). “We have had a large amount of RSV in the last couple of months, which is atypical for this seasonal virus,” Walensky said. “We did not see some of these respiratory viruses last year because we were taking those prevention and mitigation strategies [for COVID-19].”

CDC surveillance conducted at Vanderbilt University in Nashville confirms this unusual emergence of RSV, said William Schaffner, MD, professor of preventive medicine at the school and medical director of the NFID.

“We have seen an unseasonal increase with RSV, and that’s continuing,” he said. “Is that a harbinger of a worse influenza season? We don’t know, but we certainly don’t want a ‘twindemic’ of both COVID and influenza. Let’s get vaccinated against both.”

As the discussion turned to why people historically avoid the flu shot, Schaffner was not amused when a reporter asked, “How do we really know the flu vaccine does not cause flu?”

“You cannot get flu from the flu vaccine. That’s an old myth — please, you can’t do that,” an exasperated Schaffner said. “Virtually all the vaccines are made up of only parts of the virus, so there is no way that they can recreate the virus in your body to give you influenza. [No one] can hide behind that as a reason not to get vaccinated. As we say in Tennessee, ‘That dog won’t hunt.’”

Since the discussion had been breached by serious misinformation, Schaffner took the time to explain why the live, attenuated nasal spray vaccine cannot give anyone flu either.

“It is miracle of modern science that the virus can stimulate your immune system, but it cannot get down into your chest,” he said. “It can’t multiply there. It’s ‘cold adapted,’ as we call it, and cannot multiply at the slightly higher temperatures down in your lungs. So even that live, attenuated virus cannot give you the flu.”

For more on this story, see the next issue of Hospital Infection Control & Prevention.

Gary Evans, BA, MA, has written numerous articles on infectious disease threats to both patients and healthcare workers. These include stories on HIV, SARS, SARS-CoV-2, pandemic influenza, MERS, and Ebola. He has been honored for excellence in analytical reporting five times by the National Press Club in Washington, DC.