How to Prepare for Flu Season: Get Vaccinated

Between Oct. 1, 2025, and May 23, 2026, an estimated 32 million to 57 million people contracted the flu, with hundreds of thousands hospitalized and 24,000 to 81,000 deaths, including 192 children, according to preliminary data from the Centers for Disease Control and Prevention (CDC).

The CDC estimates that during the 2025–2026 flu season between 390,000 and 800,000 people were hospitalized for flu. The CDC also estimates that from Oct. 1, 2025 to Sept. 5, there have been 150,000 to 260,000 hospitalizations and 16,000 to 45,000 deaths resulting from COVID-19 and 170,000 to 340,000 hospitalizations and 9,900 to 25,000 deaths resulted from respiratory syncytial virus (RSV) between Oct. 1, 2025 and June 6.

Mid-September to late October is the optimal window for people to receive the updated vaccinations to protect against severe illness this fall and winter, said David Cennimo, an infectious disease expert at Rutgers New Jersey Medical School.

Cennimo discusses what is known about the upcoming respiratory illness season and how to protect yourself.

The 2026–2027 influenza season is predicted to peak sometime between late fall and early spring. While it is too early to predict the severity of the season, many experts have raised concerns that the decrease in vaccination rates could lead to an increase in number and severity of infections.

Influenza cases in Australia — winter in the Southern Hemisphere — are increasing but seem to be like the past few years. There are no preliminary data available to estimate influenza vaccine effectiveness currently.

The 2026–2027 U.S. flu vaccine is trivalent, meaning that it contains three different strains of influenza predicted to be most like what will be seen this year. The vaccine last year was also trivalent. The World Health Organization and CDC have updated the recommended strains included in the vaccine to better match circulating viruses. Particular attention was paid to the subtype of the H3N2 virus that was widely circulating last year. The updates are hoped to provide a better match during this season.

Slightly different virus strains are used for the egg-based vaccine versus cell culture–based vaccines. These changes address the ability of the virus to replicate and provide the best vaccine. At the individual patient level, they are interchangeable.

The only advice I routinely give related to the specific type or brand of vaccine is for people 65 or older to attempt to get a “high dose” or adjuvanted flu shot. These stimulate more response in older immune systems. However, if they are not available, a standard influenza vaccine should be given.

Multiple studies have demonstrated significantly reduced symptoms and a milder infection in vaccine recipients who become infected.

Recently, an mRNA-based influenza vaccine was approved by the FDA. This technology is similar to that proven effective in the COVID-19 vaccines and will allow more rapid fine tuning of the vaccine components. For now, the vaccine has full approval for ages 50 to 64 and accelerated approval for people 65 and over. This is a result of how the initial studies were done, and we expect to see the approvals expand as more data are accrued this year.

In a clinical trial leading to approval, the mRNA vaccine had a 26% increase in efficacy compared with standard flu vaccine. More patients did report mild, self-limited side effects such as pain at the injection site, but these resolved quickly and were not serious. The overall recommendations for influenza vaccine have not changed to prioritize any one type of vaccine and patients are encouraged to vaccinate with whatever is available.

There are no updated COVID recommendations from the CDC. Major medical societies continue to recommend COVID vaccination for all adults with particular emphasis on those over 65.

RSV is a common respiratory virus that usually causes mild, cold-like symptoms. The CDC recommends that infants 8 months and younger during RSV season receive an RSV immunization unless their mother was adequately vaccinated during the pregnancy. Older babies with certain medical conditions – in their second RSV season – may remain at high risk for complications from RSV infection and may require a second immunization.

Adults ages 50 to 74 with increased risk of severe RSV infection and everyone 75 or older should consider being vaccinated with one of three available RSV vaccines. Pregnant people should consider being vaccinated with the Abrysvo vaccine between 32- and 36-weeks gestation. Currently, RSV vaccines are only recommended for a one-time dose.

The influenza vaccine is effective for about six months, so if you get vaccinated too early there is a chance your immunity might wane. Children receiving their first influenza vaccine need a second dose at least four weeks later. Check with your doctor. The RSV season varies but usually starts in the fall and the rates of COVID-19 tend to increase in fall and winter.

Since RSV season starts in October, vulnerable people should receive the vaccine as soon as possible.

Extremely rare side effects – like allergic reaction – can happen, but the risk is still lower than with many other common medications. You can get a flu shot even if you are allergic to eggs. Serious reactions to the small amount of egg protein in flu vaccines are unlikely.

The vaccines take two weeks to be effective, so people still could contract these viruses during this period. COVID-19 vaccines contain no live virus so there is no way to become infected from the vaccine. With the flu vaccine, live viruses are grown but killed so there is no possibility of infection after vaccination, either.

Flu symptoms can be confused with COVID. If you start feeling ill, it is important to quarantine and test for COVID-19 to rule it out.

The symptoms for RSV are like the common cold. They tend to run their course with only mild intensity in adults and older children. In infants and the elderly, symptoms tend to be more severe and can include fevers and wheezing.

References:

1. https://www.cdc.gov/flu-burden/php/php/data-vis/2025-2026.html

2. https://gis.cdc.gov/grasp/fluview/pedfludeath.html

3. https://www.cdc.gov/flu-burden/php/php/data-vis/2025-2026.html

4. https://www.cdc.gov/covid/php/surveillance/burden-estimates.html

5. https://www.cdc.gov/rsv/php/surveillance/burden-estimates.html

6. Associate Program Director, VA New Jersey Health Care System, Assistant Professor, Medicine-Pediatrics Infectious Disease, https://njms.rutgers.edu/departments/medicine/med_peds_residency/associate_directors.php#:~:text=Board%20of%20Pediatrics.-,David%20Cennimo%2C%20MD,-Associate%20Program%20Director

7. https://www.fda.gov/vaccines-blood-biologics/vaccines/mflusiva

8. https://www.ama-assn.org/public-health/prevention-wellness/doctors-united-respiratory-virus-vaccine-recommendations

(Newswise/MF)