Breast Cancer and the Flu Shot: Is It Safe?

Influenza, also called the flu, is a respiratory illness caused by a virus. Usually, the flu causes symptoms like fever, muscle pain, fatigue, runny nose, and cough. However, some patients – such as people over 65 and people with chronic health conditions – may develop serious flu complications like bronchitis and pneumonia.

The influenza vaccine, or seasonal flu shot, is an annual shot that offers effective protection against the flu viruses that are likely to spread in a given year. Some people with breast cancer wonder whether they should get the seasonal flu shot. 

The flu shot is safe for people with breast cancer. People with breast cancer risk developing serious illnesses and complications from the flu, and vaccination can help to reduce the risk of complications. 

Read on to learn more about the flu shot and breast cancer, including benefits, potential side effects, which type of flu shot to take, and more.

Is the Flu Shot Safe and Effective for People with Breast Cancer?

According to recommendations from the Centers for Disease Control and Prevention (CDC), most people ages 6 months old and older in the United States should get a flu shot every year.

The flu shot has been found to be both effective and safe for most people with breast cancer, including people undergoing cancer treatment. Studies show that the seasonal flu shot significantly reduces the risk of hospitalization, severe illness, and death from influenza among people with cancer.

Certain cancer treatments, such as intensive radiation or chemotherapy, may make the flu shot and other vaccines less effective. If you are receiving treatment or about to start treatment for breast cancer, let your healthcare provider know. They may suggest that you get the seasonal flu shot two weeks before or two weeks after receiving chemotherapy.

In the United States, vaccines undergo rigorous testing to ensure they are safe before being authorized for use. Adverse reactions are rare, even for people with cancer and other serious medical conditions.

Which Type of the Flu Shot Should People with Breast Cancer Get?

The most common form of the flu shot is the inactivated influenza vaccine (IIV), which contains a dead (inactivated) version of the virus that causes influenza. It’s safe for most people with breast cancer to receive the standard-dose inactivated flu vaccine. 

Other types of flu shots – such as the recombinant influenza vaccine (RIV), or Flubok Quadrivalent – contain higher doses to offer greater protection for older and high-risk adults. Like inactivated flu vaccines, the recombinant flu vaccine is safe for most people with cancer.

However, the live attenuated influenza vaccine (LAIV), or nasal spray flu vaccine, contains a live (although weakened) version of the flu virus and may not be safe for people with breast cancer.

According to the American Cancer Society, most people with cancer should avoid live virus vaccines, including the nasal mist flu vaccine. This is especially true if you are currently undergoing cancer treatments that can affect your immune response.

Are There Any Side Effects of Taking the Flu Shot?

Side effects of the flu shot are usually mild and typically resolve without intervention within a couple of days. Flu shot side effects may include:

• Pain, redness, and/or swelling at the injection site
• Fever
• Headache
• Muscle pain
• Fatigue
• Nausea

In some cases, people may faint after taking a vaccine, including the flu shot. Very rarely, getting the flu shot can lead to Guillain-Barré syndrome—an autoimmune condition that causes problems with the nerves, such as numbness and weakness.

Risks of Influenza for People With Breast Cancer

People with breast cancer have a higher risk of serious flu complications, including pneumococcal diseases (infections, such as pneumonia, caused by Streptococcus pneumoniae bacteria), hospitalization, and even death. Studies suggest that around 9%–33% of people with cancer who contract influenza die from flu-related complications.

Both breast cancer and common breast cancer treatments, such as radiation and chemotherapy, can weaken the immune system and make you more vulnerable to infection and disease. People with cancer are more likely to have comorbidities (co-occurring conditions such as diabetes and kidney disease) that can increase their risk of becoming seriously ill.

Breast cancer survivors also have a higher chance of developing complications from the flu. One 2020 study found that cancer survivors were more likely to develop flu complications up to five years after their initial diagnosis.

Meanwhile, a 2017 study found that breast cancer survivors—especially older women—had a significantly higher chance of being hospitalized for a long time due to influenza symptoms.

What Should People Avoid Before Taking the Flu Shot?

It’s best to avoid taking nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and Tylenol (acetaminophen), for a few days before taking the flu shot. Over-the-counter (OTC) pain medications may weaken the effects of the vaccine.

Talk to your healthcare provider before getting the flu shot if you:

• Are currently undergoing radiation therapy or chemotherapy
• Are moderately or severely ill

Where Does the Flu Shot Come From?

To monitor flu samples on an ongoing basis, the World Health Organization (WHO) operates 144 influenza centers across the world, including seven in the United States. The seasonal flu shot is created based on the four types of flu A and B viruses that are most likely to spread in a given area, according to the annual data from these influenza surveillance centers.

The Food and Drug Administration (FDA) has approved three ways to produce seasonal flu vaccines, including:

• Egg-based manufacturing: For over 70 years, an egg-based production process has been used to create both the flu shot and the nasal flu vaccine. In this process, the selected candidate vaccine viruses (CVVs) are grown inside chicken eggs before being extracted and either killed or weakened for use in the flu vaccine.
• Cell-based manufacturing: In 2016, an egg-free cell-based flu shot manufacturing process was approved by the FDA. The cell-based manufacturing process uses mammalian cells instead of eggs to allow for the replication of CVVs. 
• Recombinant technology: Recombinant flu vaccines are still rarely used in the United States. Recombinant technology uses a synthetic form of a gene and a piece of a protein that is found on the flu virus to “teach” the body to protect against the flu.

Where Can You Get the Flu Shot?

You can get the flu shot – typically for free or at low prices – at many locations, including:

• Health departments
• Vaccination clinics
• A healthcare provider’s office
• Local pharmacies
• Schools
• Workplaces

If you’re not sure where to find a flu shot, you can talk to your healthcare provider, contact the local health department, or search through the CDC’s VaccineFinder. You can also call the CDC’s hotline at 800-232-0233 (TTY 888-720-7489) or text your ZIP code to 438829 (GETVAX) to find out where to get a flu shot in your area.

When Should You Get the Flu Shot?

Most people with cancer can get the flu shot on the typical recommended schedule.

The CDC recommends that most people get vaccinated in September or October, before annual flu season begins. People age 65 and older should usually wait to get vaccinated until after July or August to ensure that they get the maximum protection during flu season. However, the shot can still make a difference even if you can’t get vaccinated until later in the year.

Summary

People with breast cancer and who have had breast cancer have a higher chance of developing serious or even life-threatening complications from influenza, also known as the flu. The seasonal flu vaccine effectively protects against the flu virus and possible complications, such as pneumonia and sinus infections. 

According to the CDC, most people ages 6 months old and above should get an annual flu shot. Flu shots are effective and safe for people with cancer, including people with breast cancer.

Most flu vaccines side effects are mild to moderate and don’t require any additional treatment. However, people with breast cancer should typically avoid live vaccines, such as the nasal spray flu vaccine.

A Word From Verywell

If you have breast cancer, it’s important to protect yourself from the flu and related complications with a flu shot. Talk to your healthcare provider about when, where, and how to get the flu shot.