As the busy holiday travel season approaches, health experts are warning that the upcoming holiday season may bring more than just crowded airports and flights.

While COVID-19 cases have been on the decline this summer, the Centers for Disease Control and Prevention (CDC) has released early projections hinting that this year’s respiratory illness season could mirror—or even exceed—last year’s. Unfortunately, that resurgence could cause new challenges for the millions of Americans planning to travel this winter.

Here’s what health officials say could be in store for travelers and the people working to keep holiday flights on schedule.

The CDC Expects A Surge In Respiratory Illness This Holiday Travel Season

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According to the CDC, hospitalizations from COVID-19, the flu, and Respiratory Syncytial Virus (RSV) are expected to be about the same as last year. The agency also reports that last year’s flu season was unusually severe, causing the most hospitalizations out of all the aforementioned respiratory illnesses. While back-to-back high-severity flu seasons are rare, they’re not impossible.

Although the overall peak is expected to look similar to 2024–2025, health officials warn that several factors could worsen outcomes.

These include:

• The rise of a stronger or more evasive COVID variant
• A dominant flu strain with more severe symptoms
• Fewer people getting vaccinated for COVID, flu, or RSV

Timing also matters. COVID and RSV typically peak around late December or early January, while flu activity often peaks anywhere between December and February—making it likely that all three illnesses could overlap at once.

Why Do Respiratory Illnesses Peak During The Winter Travel Season?

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For years, researchers believed that cold and flu season hit hardest in winter simply because people spend more time indoors. But a 2023 study published in the “Journal of Allergy and Clinical Immunology” suggests there’s more to the story.

According to the research, the nose has its own built-in defense system against viruses. When nasal cells detect something that looks like a virus, they release tiny protective particles called extracellular vesicles (EVs) through a process called the TLR3 signaling pathway. These EVs defend the body by carrying small genetic materials that strengthen the body’s antiviral defenses and attaching directly to viruses to prevent them from infecting other cells.

However, exposure to cold air weakens this system. When the temperature drops, the nose produces fewer EVs, and the ones that do form aren’t as effective at fighting off viruses.

“We’ve uncovered a new immune mechanism in the nose that is constantly being bombarded, and have shown what compromises this protection. The question now changes to how can we exploit this natural phenomenon and recreate a defensive mechanism in the nose and boost this protection, especially in colder months,” said Distinguished Professor of Pharmaceutical Sciences at Northeastern University, Mansoor Amiji, in an HMS news release.

So, while being indoors and traveling during the holidays may make it easier for germs to spread, scientists now know the main cause lies in how cold weather physically reduces the body’s natural immune defenses.

How A Winter Illness Surge Could Disrupt Flights And Holiday Travel Plans

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This winter, the main concern isn’t only travelers getting sick. It’s how respiratory illnesses among staff could throw the travel industry off balance. As cold weather helps these viruses spread more easily, airports and airlines across the U.S. could see an uptick in employee callouts during one of the busiest seasons of the year. CDC data backs this idea up.

According to a report from the CDC’s National Institute for Occupational Safety and Health (NIOSH), the workplace is one of the most common places to catch the flu:

“Because workers often share office space and equipment and have frequent face-to-face contact, the workplace can be an important setting for influenza transmission. Nearly two-thirds of adults in the United States participate in the workforce, and estimates of influenza attack rates for working-aged adults (18–64 years) can be as high as 14.3% in a given influenza season.”

More specifically, the report states that workplace absenteeism during the 2017–2018 flu season increased sharply starting in November and peaked in January. The biggest jumps were among men, workers between 45 and 64, and employees in Regions 6 (Arkansas, Louisiana, New Mexico, Oklahoma, and Texas) and 9 (Arizona, California, Hawaii, and Nevada) of the U.S. Department of Health and Human Services, with the highest absences occurring between December and March.

A 2023 study published in “Transportation Research Part E: Logistics and Transportation Review” found that airlines in particular will feel the pressure of staffing gaps due to seasonal illnesses. They rely on reserve crews to fill in, but utilizing them too early often makes it harder to recover from disruptions that happen later on. Additionally, researchers pointed out that there’s still very little guidance on how airlines can maintain reliable schedules during the tracking period, when new disruptions often arise.

The Transportation Security Administration (TSA) and other federal agencies, such as the Federal Aviation Administration (FAA), are also likely to feel the strain of a surge in respiratory illnesses. Ongoing staffing challenges have already left both agencies operating with skeleton crews, a situation made worse by the current government shutdown. If the shutdown continues into the busy holiday season, limited personnel could amplify the impact of any illness-related absences.

For travelers, this all means that flight reliability during the holidays depends heavily on what happens behind the scenes. If too many airline employees call out sick or reserve crews are already stretched thin, carriers have less room to respond to last-minute problems. That can lead to more delays, cancellations, and rebookings, especially when travel demand is high.

How To Stay Healthy While Traveling During Peak Illness Season

With respiratory illnesses expected to rise this winter, the CDC recommends making sure you’re up to date on vaccines that apply to you. The agency’s new 2025 COVID-19 vaccine guidance is now tailored more closely to individual health factors, which the agency calls “shared clinical decision-making.” This approach means that physicians, nurses, and pharmacists can help determine the right timing and type of vaccine for each person. However, health professionals warn that the new guidance is potentially confusing and could actually reduce the number of Americans who get the vaccine.

Infectious disease doctor Buddy Creech shared his concerns in an interview with TODAY:

“We know that when we have softer recommendations for vaccines, uptake goes down. Patients tend to think they’re not as important as a strong recommendation that everyone should get it,” he said.

Beyond vaccination, there are several other ways to protect yourself from getting sick while traveling. One less obvious step is to keep your nasal passages moist. A study from Yale University School of Medicine found that dry air weakens the body’s natural defenses by slowing mucus clearance—the process that helps sweep viruses and bacteria out of your airways—and reducing immune activity in the nose. Using a humidifier or saline nasal spray may help the body recover faster from respiratory infections.

Another way to stay healthy this winter is by getting enough sleep. According to the NIOSH, chronic sleep loss can weaken the immune system and lower antibody production. In one study, participants who slept just four hours a night for several days produced more than 50% fewer antibodies after a flu vaccination compared to those who got normal rest. Mayo Clinic recommends that adults aim for at least seven hours of sleep per night, though ideal sleep duration varies by age.

How Many Hours Of Sleep Does Each Age Group Need?

Additionally, the CDC notes that viral particles spread more easily indoors, where the air is often stagnant. Opening a window for a few minutes several times a day to ventilate can help clear the air and reduce the buildup of airborne viruses.

Other simple ways to stay healthy during the holiday travel season include:

• Staying hydrated with water
• Washing hands frequently and thoroughly
• Disinfecting devices and high-touch surfaces
• Using contactless payment and check-in options

While some travel disruptions may be unavoidable during this holiday season’s illness surge, there are still plenty of ways for both travelers and those working in the travel industry to stay healthy. What are you planning to do to reduce your risk of respiratory illness this winter?