Your best shot for avoiding the seasonal flu - Flu shots 

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Seasonal influenza, or flu, can cause significant illness. During the last season 2024-2025, there were 51 million illnesses, 710,000 hospitalizations, and around 45,000 deaths. Influenza vaccines, commonly called flu shots, are your best defense against reducing your chance of getting influenza and even more powerful against preventing severe illness.

Here are answers to some of the more common questions we’re hearing about seasonal flu and flu shots.

How does the virus spread?

The flu virus spreads easily. You can contract it when an infected person coughs, talks or sneezes and droplets get in your nose or mouth. Less commonly, you can also get the flu by touching something that has the virus germs on it, then touching your eyes, nose or mouth.

What types of flu shots are available?

There are two types of influenza vaccines now, one made of inactivated or killed influenza and the other is an mRNA vaccine recently approved by the FDA and available in pharmacies our community.

• The inactivated flu vaccine comes in a standard dose that’s given to people over the age of six months, as well as an enhanced flu vaccine that is recommended for people 65 and over. The enhanced vaccine (formerly known has high dose) gives older individuals a higher dose of the vaccine to try to improve the immune response and protection from the vaccine.
• The new mRNA vaccine showed about 27% greater efficacy for preventing lab-confirmed influenza A or B in all ages compared to standard dose inactivated flu vaccine. Clinical outcomes focused on people over 65 years old are still pending but immunologic response from mRNA is greater than enhanced influenza vaccine.

There also is a nasal spray flu vaccine that contains a live attenuated virus, which is available for certain groups of people. Learn more here.

Which type of flu shots will be given at BCH clinics?

Patients coming into a BCH clinic will receive the standard dose inactivated vaccine, which is quadrivalent. A quadrivalent flu vaccine is designed to protect against four different flu viruses, including two influenza A viruses and two influenza B viruses.

For people 65 years and older, the enhanced quadrivalent influenza vaccine is now recommended and is available at BCH for the 2026-25 flu season.

Nasal spray flu shots and the new mRNA influenza vaccine will not be available at our clinics, but can be found at some pharmacies in the community. Be sure to call ahead if you are looking for a specific type of flu shot.

Who should get a flu shot?

A yearly flu shot is recommended for most everyone 6 months of age and older.

When's the best time to get the flu shot?

It is best to get the flu shot as soon as it becomes available in your area, which typically starts in September. The flu shot should not be delayed. If you receive the vaccine by the end of October, you will be fully protected for holiday travel in November and December.

If you’re pregnant, should you get a flu shot?

YES! All pregnant individuals should get the flu shot. First, the inactivated or killed flu vaccination is safe during pregnancy. Second, illness from influenza can be more severe for the pregnant person. The added benefit of the flu shot is that antibodies formed from influenza vaccination are passed on to your newborn, as babies can't get the flu shot until they are 6 months old. Just be sure to get the shot, not the nasal spray.

In addition, the new mRNA influenza vaccine does not have pregnancy-specific safety and efficacy data yet so a pregnant person should receive the standard inactivated flu vaccine.

How effective are flu shots at preventing the flu?

Effectiveness of the flu vaccine is closely monitored by the Center for Disease Control and Prevention (CDC) and changes annually depending on a variety of factors, including whether the vaccine matches circulating strains of the influenza virus with the average vaccine efficacy for preventing outpatient visits around 30%, while vaccine efficacy is higher for prevention of hospitalization ranging from 40% to 60%.

What are the flu shot side effects?

Many people experience no side effects. If you do, they only last for a day or so. The most common side effect is pain where the vaccine is injected, but a smaller number of people will experience generalized achiness, fever, tiredness and headache. Like COVID-19 mRNA vaccines, the influenza mRNA vaccine has a higher reactogenicity, meaning these side effects may be more prominent but are still transient.

Do the vaccines at BCH contain thimerosal?

No, the vaccines at BCH do not contain thimerosal, because we use single-dose or single-use vials. Thimerosal is a preservative that is present in very small quantities in multi-dose vials of vaccines, and studies have shown that this preservative is safe.

Reviewed and updated by Dr. Amie Meditz of BCH Beacon Center for Infectious Diseases

Read more about common vaccine myths here.