Influenza, commonly referred to as “the flu,” is a contagious illness caused by influenza viruses. The viruses affect the respiratory system (the organs involved in breathing) and often cause symptoms such as fever, cough, sore throat, stuffy or runny nose, body aches, chills, fatigue, and headache. In addition, some people may experience vomiting and/or diarrhea.

Usually these symptoms last a few days to less than two weeks. However, people living with cancer and cancer survivors are more likely to get sicker from the flu and develop complications, including pneumonia, which can lead to hospitalization or death. You can decrease your risk of flu by being vaccinated and taking other precautions.

The importance of flu vaccination

Cancer and cancer treatments, such as chemotherapy, radiation therapy, and bone marrow/stem cell transplant, weaken the immune system, which protects the body from infection [1] and disease. Vaccines (sometimes called vaccinations or shots) train the immune system to recognize and destroy harmful substances, such as flu viruses, before they can cause disease.

Unfortunately, the immune system’s response to flu viruses decreases over time, which means that anyone six months and older should be vaccinated against the flu every year. Getting vaccinated each year is especially important for people with cancer and cancer survivors, as well as their family members, friends, and caregivers, in order to stay protected throughout each flu season. Sometimes, people with cancer should not receive the flu vaccine, though, so talk with your doctor before getting vaccinated.

Types of flu vaccines

Flu viruses are constantly changing so new strains of flu virus usually appear every year. This year’s flu vaccines protect against the three viruses experts have predicted will be the most common during the 2012-2013 flu season, including the H1N1 virus (previously called “swine flu”). There are four ways you can be vaccinated.

Regular flu shot. The flu shot is injected into the muscle of the arm with a needle. It contains a virus that is not alive, which means you cannot get sick from the shot.

Intradermal flu shot. First made available last year, this type of flu shot is injected into the skin (intradermal) rather than the muscle. It also uses a much smaller needle than the regular flu shot. The vaccine is approved for use in adults ages 18 through 64.

High-dose flu shot. This is a flu vaccine specifically for people ages 65 and older. Because the immune system weakens with age, this vaccine is designed to give older people a better immune response and better protection against the flu.

Nasal spray. The nasal spray contains a weakened form of a live virus that is squirted into the nose.

If you are undergoing cancer treatment or have a history of cancer, it is recommended that you get the flu shot instead of using the nasal spray. If your immune system is in a particularly weakened state, caregivers and other household members should also choose a shot instead of the spray. Talk with your doctor about which flu vaccine is right for you.

When to get vaccinated

Annual flu vaccinations typically begin in September in anticipation of flu season, which can start as early as October and end as late as May. Although it is best to get a flu shot before flu season begins, the vaccine is still beneficial if you receive it later in the season. After receiving a shot, it takes your body two weeks to produce the antibodies (a substance your immune system makes to fight illness) that will protect you from the flu.

If you are scheduled to receive cancer treatment that will suppress your immune system, it is best to get a flu shot before treatment begins. For the best response to the vaccine during cancer treatment, get the shot when your blood cell counts are near normal, not when they are at their lowest (usually seven to 14 days after treatment). Talk with your doctor for more information.

Other ways to reduce your risk of getting the flu

The flu is thought to spread primarily from person to person through droplets that travel through the air when a person infected with a flu virus coughs or sneezes. These droplets can infect you if they land in your mouth or nose, or if you touch an object they have fallen on and then touch your mouth, nose, or eyes.

If you received cancer treatment within the past month, or if you have a form of blood cancer or lymphatic cancer, call the doctor if you have been near someone who has the flu. People who have recently undergone a bone marrow/stem cell transplant or are currently receiving chemotherapy, as well as some long-term survivors, may have weakened immune systems that make them more likely to catch the flu. You may be prescribed an antiviral drug, which can help stop the virus from infecting your body.  

If you have not had treatment within the past month, or if you are a cancer survivor, and you think you have been exposed to the flu, you should also contact your doctor to discuss if you need an antiviral drug.

In addition, you can take the following steps to reduce your risk of getting the flu:

• Wash your hands often with soap and warm water and thoroughly dry them. If you cannot wash your hands, use an alcohol-based hand sanitizer instead.
• Do not get close to someone who is sick or appears ill.
• Ask people not to visit you if they are sick or live with someone who has the flu.
• If you have to be around someone who has the flu, ask that person to cough and sneeze into a tissue or into his or her sleeve.
• Using soap, disinfectant, or rubbing alcohol, wipe off the phone and other items that a sick person touches before you use them. Flu viruses can live up to eight hours on the surface of objects.
• Try not to touch your nose, mouth, or eyes after touching shared objects or shaking hands with someone.
• Avoid using products that are not likely to prevent the flu. The U.S. Food and Drug Administration describes common types of health care fraud (deception) [2].

What to do if you “catch” the flu

• If you have received cancer treatment within the past month or have a form of blood cancer or lymphatic cancer and develop flu symptoms, call your doctor immediately. You may be prescribed an antiviral drug, which can make the flu milder and help it go away faster. These drugs work best if you take them within 48 hours after your symptoms start.
• If you are receiving cancer treatment and have the flu, contact your doctor because you may need to postpone treatment until you get better.
• Take care to not spread your germs. Except for doctor’s visits, stay home and rest. You should not go out until 24 hours after your fever has gone away (if you are running a fever).

More Information

Cancer and the Winter Months [3]

When to Call the Doctor During Cancer Treatment [4]

Additional Resources

Centers for Disease Control and Prevention (CDC): Seasonal Influenza (Flu) [5]

CDC: What You Should Know for the 2012-2013 Influenza Season [6]

Cancer & the Flu [7]