There are currently two forms of vaccinations available; a shot and nasal spray form. The nasal spray form is a live attenuated (weakened) internasal vaccine (LAIV) and does not contain thimerisol.
The nasal spray flu vaccine does contain live viruses. However, the viruses are attenuated (weakened) and cannot cause flu illness.
The weakened viruses are cold-adapted, which means they are designed to only cause infection at the cooler temperatures such as those found within the nose. This means that the viruses cannot infect the lungs or other areas where warmer temperatures exist.
The nasal spray vaccine has been in use with seasonal flu since 2003.If your child has ever received a Measles, Mumps, Rubella (MMR) or Varicella (Chicken Pox) vaccine, they have received a live vaccine.
Some children and young adults 2 years to 17 years of age have reported experiencing mild reactions after receiving seasonal nasal spray flu vaccine, including runny nose, nasal congestion or cough, chills, tiredness/weakness, sore throat and headache. Some adults 18 years to 49 years of age have reported runny nose or nasal congestion, cough, chills, tiredness/weakness, sore throat and headache. These side effects are mild and short-lasting, especially when compared to symptoms of influenza infection.
The nasal spray vaccine is recommended for healthy people 2 years to 49 years of age. It is important for those who are able to take the nasal spray vaccine to do so rather than choosing the shot. If you refuse to get the nasal spray, please know that you are taking it away from someone who can only get the injection because of a chronic illness. The nasal spray form is just as effective as the shot from for the recommended age groups. In one large study among children aged 15-85 months, the seasonal nasal-spray flu vaccine reduced the chance of influenza illness by 92% compared with placebo. And both vaccines are considered to be effective against the 2009 H1N1 virus.
People who are in close contact with immunocompromised persons being cared for in a protective environment should not get the nasal spray, but it is safe to be around anyone else and cannot be passed to them.
The flu shot injection vaccine is an inactivated vaccine that contains thimerisol. Thimerisol is a preservative that is used to keep the vaccine free from germs. Some people have suggested that thimerisol might be related to autisim. However, in 2004 a group of experts at the Institute of Medicine (IOM) reviewed many studies looking into this theory, and found no association between thimerosal and autism. Additional studies since then have reached similar conclusions.