Influenza Vaccine: The Basics

Medically Reviewed by Jennifer Robinson, MD on June 19, 2020

The most effective way of preventing the flu is with an influenza vaccination. Every fall you should be immunized against strains that have developed since the previous outbreak. If you are vaccinated against three or more strains, you may still come down with flu, but symptoms are likely to be milder than they would have been had you not had an influenza vaccination.

Influenza vaccine is available through physicians and public-health facilities and many companies provide flu vaccines on-site for their workers. Because influenza is a serious threat, the CDC recommends vaccination for everyone 6 months of age and older and others at high risk of flu complications:

  • Adults 65 and older
  • Those with chronic medical conditions, such as diabetes and asthma
  • Pregnant women
  • People with a weakened immune system, like those with HIV/AIDS 

The seasonal flu vaccine is available in three forms. One is the injectable vaccine made from an inactivated virus. This form is usually given as a single injection and is approved for people 6 months of age or older. 

Another form is given as a nasal spray called FluMist. This form of the vaccine is a live and weakened form of the flu and is approved for all healthy people 2-49 years of age who are not pregnant. If you are pregnant you can only receive the injectable form. The CDC also has recommended the nasal spray vaccine for healthy children 2 years and older without preference over the flu shot. 

 There is also a “needle-less” option for people 18-64 years old:  the jet injector vaccine with Afluria, which uses a tool with high pressure to deliver the vaccine.

All of the vaccines are given as a single dose, although children who are receiving vaccination for the first time receive two. Some people develop low fever and muscle aches as side effects of the vaccine.

Also available:

  • Intradermal shots use smaller needles that only go into the top layer of the skin instead of the muscle. They're available for those ages 18 to 64.  If you have severe egg allergies you should get the flu shot from a doctor who can treat a severe allergic reaction -- either at your doctor's office, a hospital, a clinic, or a health department.
  • Egg-free vaccines are now available for those aged 18 and older who have severe egg allergies.
  • High-dose vaccines are meant for those ages 65 and older, when available, and may better protect this group from the flu.

The medications baloxavir (Xofluza), oseltamivir (Tamiflu), peramivir (Rapivab), or zanamivir (Relenza), can prevent both influenza A and B. These antiviral medications can also help treat swine flu symptoms and shorten the number of days you are sick.

Here are more preventive measures you can take during flu season and to avoid getting swine flu:

  • Wash your hands with soap and water, or use an alcohol-based hand sanitizer often.
  • Quit smoking. The bad habit damages your respiratory tract. And watch the alcohol, since drinking, like smoking, can lower your resistance to infection in general.
  • Avoid sleeping in a room with someone who has flu. The virus is easily spread in the air.
  • Keep up your resistance by following a good diet, drinking lots of fluids, and getting plenty of rest. Stay warm and dry so that your body can fight off infection by flu and other viruses.


Show Sources



Immunization Action Coalition. 

American Academy of Family Physicians.

CDC: "Nasal Spray Flu Vaccine in Children 2 through 8 Years Old." 

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