FAQ About the Flu Shot

Learn More About Why You Should Get the Flu Shot

The CDC advises everyone 6 months and older to get a flu vaccine. Wondering if it’s safe? Or if it’s really worth it? We’ve got the answers here. 

By Katherine Ladny Mitchell

Q: How does the flu shot work?

A: The flu shot significantly lowers your risk of contracting the flu by helping your body build immunity against several strains of the
flu virus.

When you get a flu shot, you are exposed to three to four flu strains in an inactivated (and therefore, safe) state. These train your immune system to recognize the strains as “foreign invaders,” so the next time you’re exposed to an active strain, your body will quickly launch an immune attack to kill it off. 


Dr. Todd Rudolph, Medical Director, AFC Urgent Care/Family Care
Dr. Todd Rudolph, Medical Director, AFC Urgent Care/Family Care

Q: How is the flu shot made?

A: The flu shot is made in conjunction with several organizations including the Centers for Disease Control and the World Health Organization, according to Dr. Todd Rudolph, medical director at AFC Urgent Care/Family Care. “Every year, these organizations research which strains cause the most illness in various parts of the world. Their findings help them predict which will cause the most illness in the upcoming year and should be combined in the flu shot,” he says.

Once these strains have been determined for the coming year, manufacturers grow them in eggs, then inject them into different fertilized chicken eggs to multiply. After an incubation period, the virus-containing fluid is harvested, the virus is inactivated (or killed), and the remaining antigen is purified, tested, and dispensed into containers for distribution. The FDA then tests and approves individual lots of flu vaccine before releasing them to the public.

The 2016-2017 flu vaccines protect again the following flu viruses:
 A/California/7/2009 (H1N1)pdm09-like virus
• A/Hong Kong/4801/2014 (H3N2)-like virus
• B/Brisbane/60/2008-like virus (B/Victoria lineage)
• B/Phuket/3073/2013-like virus (B/Yamagata lineage)


Q: Is it safe?

A: Yes! The flu vaccine has been given to hundreds of millions of people for more than 50 years and it has a very good safety track record. Additionally, each year the CDC works closely with the U.S. Food and Drug Administration (FDA) and other partners to ensure the highest safety standards for flu vaccines.


Dr. Chris Snyder, Internal Medicine Physician, CHI Memorial Convenient Care
Dr. Chris Snyder, Internal Medicine Physician,
CHI Memorial
Convenient Care

Q: How effective is the flu shot?

A: Success rates can vary greatly depending on how well the strains in the vaccine “match” the most common viral strains in a given year. When the vaccine viruses closely resemble the naturally occurring ones, the flu shot can lower incidence by 50 to 60%. The CDC evaluates the effectiveness of flu vaccines each year, and this year’s vaccine is expected to be up to 60% effective.

Success rates can also vary greatly according to the health profile of the person receiving the vaccine. Overall, the flu shot benefits young children (those under 2) and older adults (those over 65) at lower rates. “Up to age 35, the flu vaccine will be 90 to 95% effective in protecting against the identified strains,” says Dr. Chris Snyder, Internal Medicine Physician, CHI Memorial Convenient Care. “After that, it grows less effective each year of age.”

Finally, effectiveness can be influenced by the timing of the vaccination. After a flu shot, the body needs about two weeks to produce antibodies – so it won’t be effective if you are exposed to the virus in the 14 days immediately following the shot.


Q: What is the best time to get the flu shot?

A: Even though pharmacies nationwide start carrying the flu shot in August, it’s best to get it around the end of October. This is because flu season typically begins in November, peaks in February, and runs through May – and the flu shot has a life span of about six months. “You don’t want to get it early only to find its effectiveness has dropped off by the time you need it the most,” says Dr. Snyder.


Q: Why do I need to get the flu shot every year?

A. Two reasons. The first is that the immunity provided by the vaccine decreases over time. As stated earlier, the flu shot has a lifespan of about six months. The second is that flu viruses are constantly mutating, so it’s likely you haven’t received protection from this year’s most threatening strains. “The flu virus is always changing and the vaccine has to be updated each year to keep up,” says Dr. Tyler McCurry, primary care physician with
Tennova Primary Care.


Q: Why get a flu shot if it’s possible I could still get the flu?

A: Even if you still get the flu, the vaccine can alleviate the severity of your illness, protect you from secondary complications (such as ear and sinus infections, bronchitis, and pneumonia), and even decrease your risk of hospitalization.

According to Dr. Snyder, getting the flu shot is like wearing Kevlar – it may not offer 100% protection, but it will prevent fatalities. “The most important thing to understand about the flu shot is that it can lessen your chance of dying,” he says.

Another factor to remember is something called “herd immunity,” which is indirect protection to those who are ineligible for the flu shot themselves or at a high risk for developing complications. “When you get the flu shot, you may be indirectly helping those who can’t get it – such as infants or those with weak immune systems,” says Dr. McCurry. “While we can’t offer these populations the vaccine, they can still be protected if fewer people around them contract the virus.”

Children under five years old, senior citizens, people with chronic illnesses and/or weak immune systems, and pregnant women (or those who have recently given birth) all have a higher risk for developing flu complications. This is why physicians strongly recommend anyone in close contact with at-risk groups be vaccinated. “Health care workers, long-term care workers, and those who work in childcare or daycare should get a flu shot,” says Dr. Rudolph.


Dr. Tyler McCurry, Primary Care Physician, Tennova Primary Care
Dr. Tyler McCurry, Primary Care Physician, Tennova Primary Care

Q. Can you get the flu from the flu shot?

A. No. However, you may experience short-term side effects as your immune system starts responding. “As your body works toward building its immunity, you can get similar symptoms of fever and muscle aches,” says Dr. McCurry. “It’s easy to mistake these for the actual flu.”

While these side effects can be irritating, they don’t typically last longer than one to two days. The good news is that they are signs your body is hard at work creating antibodies to fight the actual disease. If you are very sick, it’s probably because you were exposed to the virus before getting the shot or you caught a different cold virus.


Q. Who shouldn’t get the flu shot?

A. According to the CDC, children under six months are not old enough to receive the flu shot. Also, people with allergies to the vaccine or its ingredients – such as gelatin or antibiotics – should forego it. “Those who have an egg allergy or those who have had a previous adverse reaction to the flu vaccine are advised against vaccination,” says Dr. Rudolph.


Q. Can I get the nasal spray?

A.As of this June, the nasal spray flu vaccine known FluMist is no longer recommended for the 2016-2017 flu season. FluMist was first approved by the FDA in 2003 and subsequently used as an alternative to the standard flu shot for people between the ages of 2 and 49. However, due its recent poor performance – data from the past three years shows the spray was only 3% effective whereas the standard flu shot was 63% effective – the CDC now recommends only injectable flu shots for the upcoming season. Additionally, the American Academy of Pediatrics has issued new guidelines that say children ages 6 months and older should receive the flu vaccine by an injection this flu season.


Tips for Making the Process Easier:

• Relax your arm.
Tense muscles can make the pain worse. As best as you can, let it all hang loose when the needle goes in. Concentrate on taking slow, deep breaths.
Keep it moving.
Moving your arm immediately after the shot might be uncomfortable, but it will help spread the injected liquid and prevent the soreness from concentrating in one spot.
Pop a painkiller.
If you do suffer a low-grade fever or body aches after your flu shot, take a mild pain reliever like ibuprofen or acetaminophen for relief.

For more information, visit cdc.gov/flu.


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