Flu Vaccine Facts

from National Vaccine Information Center

• Flu vaccine, like all vaccines, only provides temporary immunity (if at all) and that immunity is qualitatively different from disease-induced immunity which provides longer lasting protection.(1)
• Flu vaccine contains three specific influenza viruses and does not protect against throat, respiratory, gastrointestinal and ear infections caused by bacteria and other kinds of viruses that cause flu-like symptoms. Only about 20 percent of all flu-like illnesses are actually flu.(2)
• When the match between the vaccine and circulating viruses is close, the inactivated flu vaccine is thought to be 70 to 90 percent effective in giving temporary immunity to selected strains in healthy persons under 65 years old. For those over 65 years old, the efficacy rate drops to 30 to 40 percent, although it is considered to be 50 to 60 percent effective in preventing hospitalization or pneumonia and 80 percent effective in preventing death from flu caused by covered strains.(3,4) [Often, however, prevalent strains are not covered by the vaccine, resulting in much less overall effectiveness. --ed]
• The most common reactions to inactivated flu vaccine are fever, fatigue, painful joints, and headache. The most frequently reported serious reaction, which usually occurs within two weeks of vaccination, is Guillain-Barre syndrome, an immune mediated nerve disorder characterized by muscle weakness, numbness, pain and paralysis that can lead to death.
• According to vaccine manufacturers, contraindications for the inactivated flu vaccine are fever, an impaired immune system, egg or mercury allergy, and history of Guillain-Barre syndrome.(3,4)
• The CDC recommends inactivated flu vaccine for women more than 14 weeks pregnant even though most inactivated flu vaccines contain the mercury preservative, thimerosal.(3,4) Mercury has been associated with brain damage and developmental delays in newborns whose mothers were exposed to high levels of mercury during pregnancy.(5)

References

1. Cox RJ, et al. January 2004. Influenza Virus: Immunity and Vaccination Strategies. Comparison of the Immune Response to Inactivated and Live, Attenuated Influenza Vaccines. Scandinavian Journal of Immunology.

2. Transcripts of the Vaccines and Related Biological Products Advisory Committee. February 20, 2003. US Food and Drug Administration, Center for Biologics Evaluation and Research. www.nvic.org/Diseases/Influenza.htm

3. MMWR Recommendations and Reports. Prevention and Control of Influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP). April 25, 2003. Centers for Disease Control.

4. Fluzone 2003-2004 Formula, Aventis Product information as of July 2003.

5. Steurwald U, et al. May 1, 2000. Maternal seafood diet, methylmercury exposure, and neonatal neurological function. Journal of Pediatrics.*