This article was updated 11/5/2025 at 2:55pm to correct the age range for individuals to receive FluMist (AstraZeneca). It is 2 to 49 years, not 2 to 50 years. We regret the error.
Following a severe 2024-2025 influenza season, the CDC expects the upcoming 2025-2026 flu season to be moderate across all ages, according to a report released at the end of August.
In addition, the CDC forecasted the combined season outlook of flu, COVID-19 and respiratory syncytial virus (RSV) as moderate and similar to the previous season. However, uncontrollable factors could worsen the season. To combat this, vaccination is key to being prepared for the upcoming season, the agency said.
A Moderate Flu Season
The CDC assessment is the product of years of surveillance and historical analysis as well as expert opinion. One reason the agency believes the season will be moderate is because there was high flu circulation last season, and it is rare for back-to-back high-severity seasons, which has not happened since the CDC began qualitatively assessing the upcoming flu season for the 2003-2004 season. “In short, yes, moderate severity seasons are ‘usual’ and more common than high-severity seasons for influenza,” CDC spokesperson Gabriel Alvarado told Infectious Disease Special Edition.
According to the CDC’s FluView, in the 2024-2025 influenza season, clinical laboratories saw 485,789 positive flu tests between Sept. 29, 2024, and May 31, 2025. Of those tests, 89.1% were attributed to influenza A and 10.9% were influenza B. The previous flu season saw nearly 140,000 fewer positive cases in a similar period (Oct. 1, 2023, to June 1, 2024). Of note, there were nearly 1,000 more influenza deaths in 2024-2025 than in 2023-2024.
Problems With Prediction
However, the outlook report noted that this classification is made with moderate confidence, and that forecasting inherently is not precise but rather is intended to give a high-level assessment to help healthcare professionals and public health officials prepare for the upcoming season. “It remains possible that the influenza season will be of high severity in one or more age groups this season,” the report said.
“Predicting the severity of influenza season is a very hazardous enterprise,” William Schaffner, MD, told IDSE. “As we say in the vaccine world, if you’ve seen one flu season, you’ve only seen one flu season. Flu seasons are so unpredictable.”
However, Dr. Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center, in Nashville, Tenn., said he agrees that you would not expect 2025-2026 to be as severe as the 2024-2025 season.
However, several factors could change these forecasts, according to the CDC, including other circulating viruses:
- A COVID-19 variant with moderate immune-escape properties could emerge this fall.
- An influenza subtype with more severe outcomes could circulate and become predominant.
- There could be reduced vaccination uptake for COVID-19, influenza and/or RSV immunizations.
- There could be reduced vaccine effectiveness in reducing hospitalizations compared with last year.
A Severe Winter in the Southern Hemisphere
Although the CDC is predicting a moderate flu season, the Southern Hemisphere is coming out of a severe respiratory season. Australia experienced a 60% increase in influenza cases over its five-year average by the end of June—only halfway through its flu season—and has seen lagging vaccination uptake, according to the Royal Australian College of General Practitioners. “The flu season in Australia was severe this year—particularly in June and July—and this falls on the heels of the 2024-2025 season, which was the worst flu season in the U.S. since the 2009 H1N1 ‘swine flu’ pandemic,” said Robert H. Hopkins Jr., MD, the medical director of the National Foundation for Infectious Diseases and a professor of internal medicine and pediatrics at the University of Arkansas School for Medical Sciences, in Little Rock.
However, Dr. Schaffner noted that looking to the Southern Hemisphere is not always an accurate predictor. Even so, both agreed that providers need to be prepared. “We should take lessons from the severe flu season in the Southern Hemisphere and our own severe 2024-2025 season in the U.S. The best step we can take is to increase flu vaccination rates for everyone age 6 months and older,” Dr. Hopkins said.
“What’s important is that we don’t want people’s decisions whether or not to get vaccinated to depend on a prediction,” Dr. Schaffner added. “We want them to just do it each and every year.”
Vaccination to Prevent Disease
Vaccination is key to preventing and reducing severe disease from these seasonal respiratory illnesses, according to the CDC. Last year, seasonal influenza vaccination prevented an estimated 240,000 hospitalizations, mostly in adults 65 years of age and older, according to a CDC report (MMWR Morb Mortal Wkly Rep 2025;74[6]:83-90).
In March 2025, the FDA recommended the strains for influenza vaccines, and vaccine manufacturers have projected they will supply the United States with as many as 154 million doses of flu vaccine this season. Following the FDA recommendation, Sanofi announced its vaccines—including Flublok, Fluzone and Fluzone High-Dose—started shipping during the summer. In July, GSK began shipping its Fluarix and Flulaval vaccines.
The U.S. population calls for a large supply. “Everyone 6 months and older, with rare exceptions, should get a flu vaccine every season,” the CDC said. In addition, at the June meeting of the Advisory Committee on Immunization Practices, the new committee members reaffirmed past flu recommendations—vaccinations for everyone 6 months and older and enhanced vaccines for those 65 and older, Dr. Schaffner said.
All seasonal flu vaccinations are trivalent (covering two influenza A strains, one for H1N1 and one for H3N2, and an influenza B/Victoria lineage virus). In addition to the intramuscularly administered egg, cell-based or recombinant-based vaccines, the nasal spray flu vaccine FluMist (AstraZeneca) is also an option. Granted a new indication in September 2024, the nasal spray flu vaccine, which is indicated for people 2 to 49 years of age, can be administered at home by the patient or a caregiver. This is the first vaccine that does not need to be administered by a healthcare professional.
“Today’s approval of the first influenza vaccine for self- or caregiver administration provides a new option for receiving a safe and effective seasonal influenza vaccine potentially with greater convenience, flexibility and accessibility for individuals and families,” said Peter Marks, MD, PhD, who was the director of the FDA’s Center for Biologics Evaluation and Research, when the supplemental indication was granted. “Getting vaccinated each year is the best way to prevent influenza, which causes illness in a substantial proportion of the U.S. population every year and may result in serious complications, including hospitalization and death. This approval adds another option for vaccination against influenza disease and demonstrates the FDA’s commitment to advancing public health.”
FluMist is an attenuated virus vaccine that is sprayed in the nose. A prescription is still required to receive the vaccine, even for home administration, and it will be available through a third-party online pharmacy.
A caregiver should administer FluMist to people 2 through 17 years of age, as individuals in this age group should not self-administer the vaccine, according to the FDA.
Fighting Safety Confusion
One big stumbling block to increasing vaccination rates is the vaccine misinformation circulating around the neighborhood and on social media. “Higher flu vaccination rates could help blunt the impact of a severe season, but misinformation about the safety and effectiveness of flu vaccines continues to make that goal an uphill battle,” Dr. Hopkins told IDSE.
Over the past three years, there has been a slight decline in flu vaccination rates, Dr. Schaffner said. “That’s been attributed to many things, not the least of which is the confusion and the turmoil that we’re currently involved in regarding recommendations,” he said. The flu vaccine isn’t a perfect vaccine, he said, but it keeps you “out of the hospital, the intensive care [unit] and the cemetery.”
Dr. Hopkins agreed. “Let me state it plainly: Vaccines for flu, COVID-19 and RSV help lower the risk of infection and, most importantly, reduce severe illness,” he said. “These benefits are seen in healthy persons and those with additional risk factors. Serious side effects are very rare.”
Dr. Hopkins said he and all of his family members, between the ages of 15 and 86, will be getting the flu and COVID-19 vaccines soon, and those who are eligible have already received their RSV shots.
Drs. Hopkins and Schaffner reported no relevant financial disclosures.
This article is from the October 2025 print issue.