The H1N1 flu is no longer considered a pandemic. This article provides historical information about pandemic H1N1 flu and will no longer be updated. Please see the Centers for Disease Control and Prevention (CDC) website for the latest information about H1N1 flu.

Most of the information below is specific to the United States. For H1N1 flu vaccine information for the country you live in, please contact or visit the website of your country's health department.

Flu shot image A vaccine is a substance used to protect people from infections caused by bacteria and viruses. The H1N1 flu vaccine is designed to protect you against the pandemic H1N1 flu virus. There are two ways you might receive the H1N1 flu vaccine:

  • Shot given in the muscle—uses inactivated vaccine containing dead virus
  • Nasal spray—uses live, attenuated vaccine containing weakened virus

The virus in a vaccine will not make you sick.

Like other flu vaccines, you should not get the H1N1 flu vaccine if you are allergic to eggs.

The live, attenuated vaccine (nasal spray) should not be given to:

  • Those younger than two years or older than 50 years
  • Anyone with a severe chronic medical condition or weakened immune system
  • Pregnant women
  • Children under 18 years old taking chronic aspirin therapy