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Vaccines Health Center

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Influenza Vaccine (Flu Shot and Nasal Spray) for Adults

The influenza vaccine is a yearly vaccine that protects you from getting the flu, a viral respiratory illness that spreads very easily. The flu can lead to serious health complications and possibly death.

The best way to prevent the flu is to get vaccinated. There are a few types of flu vaccines:

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  • Flu shot: The flu shot is typically given to adults in a muscle in the upper arm. It is an inactive vaccine, which means it is made using a dead form of the viruses the shot protects against. The dead germs cannot make you sick. Those ages 18 to 64 can to opt for an intradermal flu shot. This injection uses a smaller needle and goes into the top layer of the skin instead of the muscle.
  • Fluzone high dose: This inactivated vaccine was developed for those ages 65 and older, because older people have weaker immune systems. It's preferred for this group instead of a regular flu shot when available.
  • Egg-free vaccines: Unlike most flu vaccines, these are not grown inside eggs. They're approved for people with a severe allergy to eggs.
  • Nasal spray: The nasal spray flu vaccine is a live attenuated influence vaccine, or LAIV. Unlike the flu shot, it is made from live, but weakened, influenza viruses. However, you cannot get the flu from the nasal spray vaccine. Only certain adults under age 50 may receive the nasal spray.

The three or four flu strains covered by the flu vaccine differ from year to year. That’s because the flu viruses are constantly changing. Scientists develop a new flu vaccine each season based on research that predicts which strains will be most likely to make you sick.

When Should Adults Be Vaccinated?

Flu seasons also vary, depending on where you live. Flu season can run from October to May. You should get vaccinated as soon as the vaccine becomes available. It takes about two weeks for the flu vaccine to start working, so you want to make sure you are fully protected as soon as possible. Generally, the seasonal flu vaccine is available from September until spring.

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