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Your Guide to the Flu Shot


Answers to your top questions about the flu vaccine

Updated November 10, 2014.

By Moira Kerrigan


A fever, aches, chills and that general worn-down feeling — let's face it, the flu is no fun. But you don't have to stock up on immune-boosting supplements or hide yourself indoors all winter to avoid the flu — you just have to roll up your sleeve. The flu shot is the best way to guard against the virus. However, just 46 percent of people in the United States got the flu vaccine in 2013, according to the U.S. Centers for Disease Control and Prevention (CDC) — and it's not simply a fear of needles that's keeping them away. Many people are confused about the vaccine and its potential side effects. We tackle 10 common concerns about the flu vaccine to help you stay healthy and flu-free this winter.


What is the flu shot, anyway?

The flu shot is made up of inactivated (dead) flu viruses. These inactivated viruses cause your body to create flu-fighting antibodies, which help you fend off the virus if you come into contact with it. This year's shot protects you against three strains of the flu, including the H1N1 virus (also known as swine flu).


Why is the vaccine necessary?

The flu is a common respiratory virus that spreads easily — usually by the droplets made when those infected with the virus cough, sneeze or talk. And while it's not typically thought of as a serious illness, complications that stem from the flu can be life-threatening: the flu can develop into pneumonia, or aggravate an existing chronic illness. Each year, around 200,000 people are hospitalized with the flu, and the CDC estimates that thousands die from complications associated with the virus each year. The shot is an easy, safe way to protect yourself from the flu — and to prevent spreading the virus to others.


Who should get vaccinated?

The CDC recommends that everyone over the age of six months be vaccinated to reduce their risk of contracting the flu. The vaccination is especially recommended for certain groups considered to be at a higher-risk:

  • All children between the ages of 6 months and 18 years
  • Adults over the age of 50
  • Pregnant women
  • Adults living in nursing homes
  • Health care workers
  • Childcare workers
  • Those with chronic medical conditions such as asthma, diabetes, obesity, epilepsy, or kidney or liver disease

Although the vaccine is safe for nearly everyone, there are certain groups who should not receive a flu shot. Those include:

  • Children under the age of 6 months
  • Children and adults with a severe egg allergy (the flu vaccine contains tiny amounts of egg protein)
  • Children and adults who have had a severe (life-threatening) allergy or reaction to a previous flu vaccine.
  • Children and adults who are already sick. If you have a fever, you should not get vaccinated until you're feeling healthy again.


When should I get vaccinated?

It's best to get vaccinated at the beginning of flu season, which usually starts in October and can run through May. The CDC recommends getting your yearly vaccination before December, so that the vaccine can develop protective antibodies before flu season is at its peak.


What are my options for receiving the vaccine?

Most people who choose to get vaccinated against the flu receive an injection into a muscle, typically in the arm. The flu shot is appropriate for everyone wishing to receive the vaccination.

Another option is the intradermal shot, which was first made available in the 2011-2012 flu season. This shot is injected into the skin instead of into a muscle using a shorter needle, and also contains a lower dose of the vaccine. The intradermal shot is only approved for people between the ages of 18 and 64.

A nasal spray vaccine is available for those who are a bit needle shy. The spray is made from a weakened form of the flu virus, instead of a deactivated one. Starting in 2014-2015, CDC recommends use of the nasal spray vaccine (LAIV) for healthy children 2 through 8 years of age, when it is immediately available and if the child has no contraindications or precautions to that vaccine.

Recent studies suggest that the nasal spray flu vaccine may work better than the flu shot in younger children. However, if the nasal spray vaccine is not immediately available and the flu shot is, children 2 years through 8 years old should get the flu shot. Don’t delay vaccination to find the nasal spray flu vaccine.

Work with the doctor or nurse giving you the vaccination to select the method that's most appropriate for your age, health and comfort level with needles.


What should I expect when I get vaccinated?

The vaccine carries a very low risk of side effects. The most common side effect of receiving the shot is a slight tenderness, redness or swelling where the shot was given. This can last a day or two.

You may also experience a slight fever or muscle aches for a couple days after receiving the vaccine as your body builds virus-fighting antibodies.

The nasal vaccine and the intradermal shot can both cause additional side effects. If you choose to receive the nasal vaccine, you may experience a headache, sore throat and a runny nose. The intradermal shot may cause toughness or itching at the site of the injection.


Is the flu vaccine safe for pregnant women? What about women who are breastfeeding?

The flu vaccine is safe for pregnant and breast-feeding women — in fact, it can serve as an important source of protection for both moms and their babies. Pregnancy can put added stress on a woman's heart and lungs, as well as her immune system. If you catch the flu when you're pregnant, it can lead to serious complications, like pneumonia and respiratory distress.

Pregnant or breastfeeding women who get the shot are also helping to protect their baby after birth, because children can't get a flu shot until they're six months old. The antibodies that pass through a pregnant or breastfeeding mom's body can help guard her newborn from any danger.

If you get vaccinated while pregnant, make sure you only receive one of the two injection-administered shots — the nasal spray is not recommended for pregnant women.


Will the flu shot make me sick?

No, the flu shot will not make you sick. Because the viruses used in the vaccine injection are inactivated (dead), it is not possible to contract the flu from the vaccine. The nasal spray form of the vaccine does contain weakened viruses instead of dead ones, so it is possible to experience mild side effects after receiving this vaccine. That could include a slight fever, aches, headache or fatigue. If you do feel flu-like symptoms after getting a shot, it's more likely that you were exposed to the virus immediately after being vaccinated — it can take up to two weeks for the vaccine to take effect.


If I got vaccinated last year do I have to get vaccinated again?

Yes. The antibodies your immune system produces to fight the flu virus start to fade after about six months. Even if they didn't fade, flu viruses are adaptable and change from year to year. A new vaccination each year helps keep those antibodies strong enough to fight off the latest version of the virus.


Does the shot really work?

Yes, the flu shot is generally effective in protecting against the flu virus, however the effectiveness of the vaccine varies from year to year. The scientists who develop the vaccine have no way of knowing for sure which strains of the virus will be most prevalent during each upcoming flu season. There are 130 influenza centers around the world that study different flu viruses year round to see which strains are circulating and spreading. Even though a vaccine's effectiveness can't be predicted in any given year, experts still recommend the vaccine as the most effective way to fight the flu and an essential part of keeping yourself — and those around you — healthy this winter.


Moira Kerrigan is a freelance writer living in San Francisco.


Published November 8, 2011.


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