Feb. 23, 2011 -- Combining the annual flu shot with other vaccines -- particularly the pneumococcal PCV13 vaccine -- may increase a child's risk of a seizure associated with high fever.
It's a small risk of a scary but not very dangerous seizure. About one in 25 kids under age 5 get a febrile seizure (seizure associated with high fever). Getting the two vaccines together increases this risk by about one case per 1,600 double vaccinations in children aged 12 to 23 months.
The new data come from a CDC investigation of an apparent increase in febrile seizure in kids getting flu shots, first reported in January. Preliminary results of the investigation were reported at today's meeting of the Advisory Committee on Immunization Practices (ACIP), a panel of outside experts that recommends U.S. vaccine policies.
"This adds perhaps 60 seizures per 100,000 children. And the good news is, if it were to happen, it would be on the day of or the day after vaccination, so parents can know what to look for," Frank DeStefano, MD, MPH, of the CDC's Immunization Safety Office, tells WebMD.
The PCV13 vaccine was added to the routine childhood vaccination schedule last April. It takes the place of the older PCV7 vaccine. The newly discovered risk of febrile seizure in kids who get PCV13 at the same time as seasonal flu vaccine does not change current vaccination recommendations.
"During flu season, 30% to 40% of kids with febrile seizures have the flu," says ACIP member Janet Englund, MD, professor of pediatrics at Seattle Children's Hospital. "As pediatricians who work with flu vaccine, we feel flu vaccination prevents more febrile seizures than it causes."
Febrile seizures usually occur in kids with a fever of 102 F or higher. They're usually triggered by an ear infection, a cold, the flu, or a rash. Febrile seizures triggered by vaccination are uncommon but are a rare known side effect of some vaccines.
Febrile Seizure Symptoms
Symptoms of febrile seizure are large or small spasms or jerking movement that usually last for only a minute or two. Although the child may briefly lose consciousness, febrile seizures do not cause permanent neurological damage.
Most febrile seizures are not emergencies. However, call 911 if the seizure doesn't stop after three to five minutes or the child has labored breathing or is turning blue. About a third of kids who have one febrile seizure will have another one. However, fewer than 10% of kids who experience febrile seizures will turn out to have epilepsy.
The extra risk posed by combined flu and pneumococcal vaccination did not faze ACIP members.
"If you have a busy pediatric practice, you will see one additional vaccine-related febrile seizure every year -- in the same time when you will see some 80 febrile seizures [not vaccine related] every year," says ACIP member S. Michael Marcy, MD, of Southern California Permanente Medical Group, Los Angeles.