H1N1 vaccine frequently asked questions

  • Published
  • By Nancy Driscoll
  • 452 AMW Public Health Office
MARCH AIR RESERVE BASE, CALIF. --  Since flu shots are high on everyone's windscreens, here are some answers to common H1N1 flu vaccine questions. 

Does the 2009 H1N1 flu vaccine have a preservative in it? Multi-dose vials of flu vaccine contain the preservative thimerosal to prevent bacterial growth. However, because some people are concerned about exposure to preservatives, manufacturers are producing preservative-free seasonal flu vaccine and 2009 H1N1 flu vaccine in single dose syringes. CDC recommends that pregnant women receive flu vaccine with or without thimerosal. 

Does the 2009 H1N1 flu vaccine have an adjuvant or squalene in it? Adjuvants are agents that are sometimes added to a vaccine to increase its effectiveness. There are no adjuvants (such as squalene) in either the 2009 H1N1 or seasonal flu vaccines used in the U.S. 

Can the seasonal flu vaccine and the 2009 H1N1 flu vaccine be given at the same time? Seasonal flu and 2009 H1N1 vaccines may be administered on the same day but given at different sites (e.g. shots given in different arms). However, Live Attenuated Influenza Vaccine (FluMist [nasal mist]) should not be given on the same day as an Inactivated Influenza Vaccine (FluZone, Afluria) or Novel H1N1 Vaccine; they should be separated by at least 28 days. 

What are the possible side effects of the seasonal and 2009 H1N1 flu vaccine?
Pregnant women are not known to have an increased risk of side effects from the flu vaccine. The side effects from 2009 H1N1 flu vaccine are expected to be similar to those from seasonal flu vaccines. The most common side effects following vaccination are expected to be mild, such as soreness, redness, tenderness or swelling where the shot was given. Some people might experience headache, muscle aches, fever, fatigue, and nausea. If these problems occur, they usually begin soon after the shot is given and may last as long as 1-2 days. Fainting may occur shortly after receiving any injection and has uncommonly been reported after the flu shot. Like any medicines, vaccines can cause serious problems like severe allergic reactions. However life-threatening allergic reactions to vaccines are very rare. Anyone who has a severe (life-threatening) allergy to eggs or to any other substance in the vaccine should not get the vaccine. Providers should ask patients whether they have any severe allergies or if they have ever had a severe allergic reaction following flu vaccination. 

Are the seasonal and 2009 H1N1 flu vaccines expected to be associated with Guillain-Barre Syndrome (GBS)? During the 1976 Swine Flu vaccination program in the U.S., using a vaccine virus very different than the 2009 H1N1 virus, was associated with cases of GBS, a severe paralytic illness, which occurs at a rate of 10-20 cases per 1 million adults per year, regardless of vaccination. In general, seasonal flu vaccine has not been found to increase the risk for GBS.