FDA and CDC Update on Fluzone Influenza Vaccine and VAERS Reports of Febrile Seizures in Children
January 20, 2011
The Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) routinely monitor the safety of all U.S. vaccines by using several vaccine safety surveillance systems, including the Vaccine Adverse Event Reporting System (VAERS). VAERS collects and analyzes information from reported adverse events (health problems or possible side effects) that occur after vaccination.
FDA and CDC have recently detected an increase in the number of reports to VAERS of febrile seizures following vaccination with Fluzone (trivalent inactivated influenza vaccine or TIV, manufactured by Sanofi Pasteur, Inc.). Fluzone is the only influenza vaccine recommended for use for the 2010-2011 flu season in infants and children 6-23 months of age. These reported febrile seizures have primarily been seen in children younger than 2 years of age. Data from VAERS are preliminary and serve as a sign or indication that further investigation is warranted. Further investigations are under way to assess whether there could be an association between influenza vaccination and febrile seizures, or if other factors could be involved. FDA and CDC have seen no increase in VAERS reports of febrile seizures in people older than 2 years of age following vaccination with TIV, and no increase after live attenuated influenza vaccine (FluMist, the nasal spray vaccine). In the cases reported, all children recovered and no lasting effects have been seen. Recommendations for the use of flu vaccine in children have not changed.
FDA and CDC will continue to conduct studies and provide additional information to the public and health care providers as it becomes available.
Information on Febrile Seizures
Febrile means "relating to a fever” or an unusually high body temperature. In some children, having a fever can cause a seizure. Although febrile seizures can be frightening for the child's caregivers, nearly all children who have a febrile seizure recover quickly and have no long term effects. Febrile seizures may occur with any common childhood illnesses that may cause fever, such as ear infections, colds, influenza and other viral infections, and they sometimes happen after vaccination. With regard to influenza infection, one study estimated that seizures occur in 1% of children under 5 years of age with laboratory-confirmed influenza and 9% of children who are hospitalized due to influenza virus infection. 
Approximately 1 in 25 (4%) young children will have at least one febrile seizure in their lifetime usually between 6 months and 5 years of age with the peak age between 14 and 18 months of age.
Parents and caregivers should contact their child’s health care provider if they have any questions or concerns.
About Influenza and Influenza Vaccination
The risk of severe influenza illness is higher among young children, especially children under 2 years of age. Approximately 9 out of 10,000 children 6-23 months of age require hospitalization each season for reasons related to influenza. Flu vaccine is the best way to protect against becoming ill with the flu.
Recommendations for the use of flu vaccine in children have not changed. CDC recommends that all persons ages 6 months and older receive a flu vaccine each year.
FDA and CDC Actions
FDA and CDC are conducting further analyses to investigate this preliminary finding in VAERS and will provide additional information as it becomes available. FDA is also working closely with the manufacturer to obtain additional information and investigate the situation further.
Poehling KA, Edwards KM, Weinberg GA, Szilaglyi P, Staat MA, Iwane MK, et al. The underrecognized burden of influenza in young children. N Engl J Med. 2006 Jul 6;355(1):31-40.