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There are different types of flu vaccine and ways administered to meet a variety of needs. Flu vaccines protect against the three or four viruses that research suggests will be most common. Experts do not give preference for one type of flu vaccine over another; what’s most important is that people receive the vaccine as soon as possible.

Three-component (trivalent)

  • Intramuscular (Flu Shot): Ages 6 months and older.
  • High Dose: A higher dose of antigen in the vaccine designed to give older people a better immune response and, therefore, better protection against the flu. Ages 65 and older.
  • Adjuvant: Creates a stronger immune response. Ages 65 and older.

Four-component (quadrivalent)

  • Intramuscular (Flu Shot): Ages 6 months and older.
  • Cell-based: Ages 4 and older.
  • Recombinant that is egg-free: Ages 18 and older.
  • Live attenuated influenza vaccine: ages 2 -49

Top things to know about the flu vaccine

  1. Everyone 6 months and older should get vaccinated annually. Babies and young children (6 months to 8 years) may need 2 doses of the vaccine, given at least 4 weeks apart, depending on vaccination history.
  2. A flu vaccine is the first and best way to protect against the flu.
  3. Get your vaccine as soon as it becomes available, and ideally by the end of October. It takes about two weeks after vaccination for antibodies to develop in the body that protect against flu. Getting vaccinated later in the season (November-March) can still protect you because flu season often peaks after January and can last as late as May.
  4. Getting vaccinated also protects people around you.
  5. Flu vaccine should be given to all women who are pregnant, considering pregnancy, in the postpartum period, or breastfeeding during the flu season. Vaccinating pregnant women helps protect them from flu illness and hospitalization, and also has been shown to help protect the baby from flu infection for several months after birth, before the baby can be vaccinated.
  6. Serious outcomes of flu infection can result in hospitalization or death. Some people, such as older people, young children, and people with certain health conditions, are at high risk of serious flu complications. Flu vaccination can reduce these risks.
  7. Most healthy adults may be able to infect other people beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Children may pass the virus for longer than 7 days. Symptoms start 1 to 4 days after the virus enters the body. That means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick.
  8. The flu shot doesn’t cause the flu.
  9. Make sure others in your community get vaccinated to help prevent the spread of disease.
  10. While some people who get vaccinated still get sick, flu vaccination has been shown in several studies to reduce severity of illness.
  11. During the 2016–2017 season, vaccination prevented an estimated 5.3 million illnesses, 2.6 million medical visits, and 85,000 influenza-associated hospitalizations.
  12. A 2017 study showed that flu vaccine can be life-saving in children

Why is it important to get a flu vaccine EVERY year?

  • Flu viruses are constantly changing, so flu vaccines may be updated from one season to the next to protect against the viruses that research suggests will be common during the upcoming flu season.
  • Your protection from a flu vaccine declines over time. Yearly vaccination is needed for the best protection.

Is the flu vaccine safe?
Flu vaccines have a good safety record. Hundreds of millions of Americans have safely received flu vaccines over the past 50 years. Extensive research supports the safety of seasonal flu vaccines. Each year, CDC works with the U.S. Food and Drug Administration (FDA) and other partners to ensure the highest safety standards for flu vaccines. More information about the safety of flu vaccines is available at

What about people with egg allergies?
People with a history of egg allergy of any severity should receive any licensed, recommended, and age-appropriate influenza vaccine.  Those who have a history of severe allergic reaction to egg (i.e., any symptom other than hives) should be vaccinated in an inpatient or outpatient medical setting (including but not necessarily limited to hospitals, clinics, health departments, and physician offices), under the supervision of a health care provider who is able to recognize and manage severe allergic conditions. The CDC has more information here. If you are looking for vaccine manufactured without eggs, ask your healthcare provider about Flublok or Flucelvax. 

What are the side effects of flu vaccines?

  • Flu shots: Flu shots are made using killed flu viruses (for inactivated vaccines), or without flu virus at all (for the recombinant vaccine). So, you cannot get flu from a flu shot. Some minor side effects that may occur include soreness, redness and/or swelling where the shot was given, low grade fever, and aches.
  • Nasal spray flu vaccines: The viruses in nasal spray flu vaccines are weakened and do not cause the severe symptoms often associated with influenza illness. For adults, side effects from the nasal spray may include runny nose, headache, sore throat, and cough. For children, side effects may also include wheezing, vomiting, muscle aches, and fever.
  • If these problems occur, they are usually mild and go away on their own, but serious reactions are also possible. Almost all people who receive flu vaccine have no serious problems from it.

You got the Flu – Now What?

1. Figure out if it’s influenza. Know the FACTS.

  • Fever
  • Aches (muscle/body/headaches)
  • Chills
  • Tired/Fatigue
  • Sudden Onset

2. Consider whether you need to see a doctor

If you get the flu, antiviral drugs may be a treatment option. Check with your doctor promptly if you are at high risk of serious flu complications and you get flu symptoms. People at high risk of flu complications include young children, adults 65 years of age and older, pregnant women, and people with certain medical conditions such as asthma, diabetes and heart disease. When used for treatment, antiviral drugs can lessen symptoms and shorten the time you are sick by 1 or 2 days. They also can prevent serious flu complications, like pneumonia.

If, however, you have symptoms of flu and are in a high risk group, or are very sick or worried about your illness, contact your health care provider.

3. Stay home
You may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or other necessities. Your fever should be gone without the use of a fever reducing medicine.

4. Prevent the spread
Stay away from others as much as possible to keep from infecting them. If you must leave home, for example to get medical care, wear a face mask if you have one, or cover coughs and sneezes with a tissue or the crook of your elbow. Wash your hands often to keep from spreading flu to others. Flu viruses spread mainly by droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby. A person might also get flu by touching a surface or object that has flu virus on it and then touching their own mouth, eyes or possibly their nose.