A Flu Season Primer

With the start of autumn, it is once again time to prepare for flu season. To help inform the university community about the flu and to educate members about the importance of the flu vaccine, New York Tech News tapped the expertise of Matthew Heller (B.S. ’08, D.O. ’11), an associate professor of family medicine at New York Institute of Technology College of Osteopathic Medicine.

What is the flu, and when does flu season typically occur?

The flu is a respiratory illness caused by influenza viruses. The “flu” is short for influenza and is a commonly used term for this viral illness. Symptoms include fever, chills, body aches, cough, headache, and fatigue. People typically become symptomatic a few days following exposure to the flu virus but are contagious before they are symptomatic. They typically feel fine, but unknowingly they may be spreading the virus to their family, friends, colleagues, classmates, and all those they interact with.

Symptoms typically start about three to four days after exposure with a sudden spiking fever. Symptoms may last for about a week; some, such as coughing, can last longer.

Flu season typically occurs in the fall and winter. Cases begin to increase in October and conclude in April or May. According to the Centers for Disease Control and Prevention (CDC), the “peak month of flu activity” is the month with the highest percentage of respiratory specimens testing positive for influenza virus infection during that flu season. Data on U.S. peak activity over several decades show that the flu most often peaked in February, but October, November, and April have been peak flu activity months.

Luckily, there is a vaccination that can help protect against this virus and help prevent the illness. This is a yearly vaccine known as the flu vaccine (or flu shot).

Who should get a flu vaccine, and why?

If you are over the age of 6 months, you should get a flu vaccination every year, but there are rare exceptions. If you experienced a severe allergic reaction to a dose of influenza vaccine in the past, you should avoid the flu vaccine. Similarly, if you have a severe allergy to any ingredient in the flu vaccine (other than egg proteins), you should not get the flu vaccine. Always talk to your physician about any of these potential exceptions and find out whether the flu vaccine is appropriate for you.

The flu vaccine protects you from becoming sick by developing antibodies that will protect you against the virus that causes the flu. It will reduce your chances of getting the flu and experiencing flu-like symptoms that may prevent you from going to school or work. If you were to get sick, the flu vaccine can reduce the severity of symptoms and potential complications from the influenza virus.

How effective are flu shots? How long does vaccine protection last?

The CDC continuously studies flu vaccine effectiveness. Results vary from year to year and depend on several variables. For example, for the 2025-2026 season, the influenza vaccine was less effective than in previous seasons. One of the main causes of that reduced effectiveness was the dominance of a heavily mutated variant of the influenza virus that created a rapid surge in infections.

But it is important to note that even during seasons where the flu vaccine is less effective, it still prevented hospitalizations and deaths and reduced the risk for influenza-associated outpatient visits across all age groups.

Are there vaccination side effects that people should look out for?

Most people who get the flu vaccine will not have any side effects. Those that do develop are often mild and will disappear on their own without any further treatment.

Side effects will vary based on the type of vaccine you receive. For example, if you receive the injectable vaccine, monitor the injection site for potential soreness, redness, and swelling. Side effects may also be systemic, such as a low-grade fever, headache, fatigue, and muscle aches. If you receive the vaccine via nasal spray, monitor for symptoms including runny nose, headache, low-grade fever, sore throat, and cough.

As a physician, do you see the “vaccine fatigue” phenomenon? How do you overcome it?

The “vaccine fatigue” phenomenon occurs when people develop a reduced enthusiasm for vaccination, leading to a decline in their willingness or motivation to receive the recommended vaccines over time. Many factors play a role in this phenomenon that can lead to the perceived burden and burnout of keeping up with vaccination recommendations.

One of the best ways I found to overcome “vaccine fatigue” is listening to patients. I let them tell me what their concerns are and address them specifically. If the cause is due to the uncertainty from constant changes in the vaccine recommendations, I remind them that recommendations evolve as we develop new scientific evidence. If the cause is due to the perceived low risk of complications from becoming infected with the virus, I remind them that the same virus that can cause mild symptoms in a low-risk patient can be transmitted to a high-risk patient, causing severe symptoms.

Also, it is important to note how safe the flu vaccines have been for people over the years. The CDC reports that hundreds of millions of Americans have safely received flu vaccines for more than 50 years. The body of scientific evidence overwhelmingly supports the safety of flu vaccines.

Is it possible to get the flu by receiving the vaccine?

The way influenza vaccines are developed makes them unable to cause an individual to become sick with the flu. The influenza vaccine in the injectable form contains inactive viral strains that have been treated so they cannot replicate. If a virus can’t replicate, it can’t cause an illness. The vaccine in the nasal spray contains influenza viruses that have been altered in the laboratory. The virus may replicate in cool nasal passages, but they are unable to replicate in the warm lung tissues where influenza needs to replicate to cause an infection.

Some people may perceive side effects from the vaccine as actually “getting the flu,” but the symptoms are much less severe than the actual flu and are the immune system’s response to the vaccine, allowing protection against the influenza virus.

Why is it important to take flu prevention seriously?

The flu spreads easily from person to person. When we fail to protect ourselves, we may be failing to protect others. By getting the flu vaccine every year, you help to reduce the risk of becoming infected with the influenza virus, and subsequently, reduce your chances of passing on the infection to others who may be at a higher risk for serious illness or complications.

Should someone see a healthcare provider if they think they have the flu?

If someone thinks they may have the flu, they may not necessarily need to see a doctor. They can recover at home with plenty of rest and fluids. However, if they are within a high-risk group of developing complications, or if they develop severe symptoms, they should contact their physician immediately. They may be a candidate for antiviral medication that works best when initiated within 48 hours of influenza symptom onset. High-risk populations include adults aged 65 and older, young children, pregnant women, and those with chronic health conditions. “Red flag” symptoms that warrant a trip to the emergency room include difficulty breathing, chest pain, confusion, and dizziness. Red flag symptoms in children may include rapid or fast breathing or breathing with the use of accessory muscles in the neck or between the ribs.

Besides getting vaccinated, what are the most effective steps people can take to avoid getting the flu?

Getting the annual flu vaccine lowers the risk of getting the flu or may lower the risk of becoming severely ill. When you go for the flu vaccine, consider bringing your family members and getting them vaccinated as well. With everyone in the household vaccinated against the flu, it will help prevent becoming sick with the influenza virus and reduce transmission.

Other steps to take at home and in the workplace include washing your hands often with soap and water for at least 20 seconds and keeping an alcohol-based hand sanitizer containing 60 to 95 percent alcohol handy for when you are without access to soap and water.

Cleaning high-touch surfaces can help reduce the spread of infection. When coughing or sneezing, cover your mouth with a tissue or your elbow. Keeping your hands away from your mouth, eyes, and nose will help keep germs away from those places.

Avoiding large crowds during the peak of flu season will lower your chances of getting the sick. Since some people may be contagious before they become symptomatic, it is difficult to determine who may be spreading the influenza virus at a large gathering. In addition, improving the air quality can help reduce the risk of exposure to the virus. This includes bringing in fresh air from outside or having gatherings outdoors.

If you become sick, it is important to help prevent the spread of the infection. Stay home until you feel better and the symptoms are resolving. It is best to wait until you have been fever-free for 24 hours without the use of any fever-reducing medications, such as acetaminophen or ibuprofen.

What is your best advice for flu season?

Remain educated about the impact of the current flu season. Remember that getting the flu vaccine will not only protect you but will also protect all those around you. By setting the example, others will follow.

This interview has been condensed and edited.