Scary though they may appear, febrile convulsions are both fairly common and nearly always benign in infants and young children. They usually occur as the result of a viral infection (cold or flu) or from an ear infection.
According to the NIH:
Most febrile seizures last only a few minutes and are accompanied by a fever above 101°F (38.3°C).
Although they can be frightening for parents, brief febrile seizures (less than 15 minutes) do not cause any long-term health problems.
The most likely time a child will experience febrile convulsions is between the ages of 6 and 24 months, which is also a time when most children receive a large number of childhood vaccines.
Between occasional post-vaccination fevers, and the luck of the draw, a small number of febrile convulsions have been reported in the 24 hours following childhood vaccination.
Because of these concerns, and the observation that some same-day vaccination combinations may increase the risk of seizures, researchers have gone back through the records of nearly 10 million patients looking for patterns, and prevalence, of post vaccination febrile convulsions.
What they found should be comforting for parents, as the overall risk of seeing a seizure was only about 3 in 10,000 children, and then, almost always without complications.
This study looked at childhood receipt of influenza vaccines, conjugated pneumococcal vaccine (PCV), and diphtheria-tetanus-acellular pertussis (DTaP) vaccines given alone or combinations.
They did not look at MMRV, Chickenpox, or other live vaccines, which are already known to carry a slightly elevated risk of febrile seizures.
While the absolute risks were small, the study - published today in the journal Pediatrics - found a slightly elevated risk of febrile seizure from the pneumococcal vaccine when given alone, and the flu vaccine if administered the same day as the as either the pneumococcal vaccine or DTaP.
AbstractRESULTS: Only PCV 7-valent had an independent FS risk (incidence rate ratio [IRR], 1.98; 95% confidence interval [CI], 1.00 to 3.91).
IIV3 had no independent risk (IRR, 0.46; 95% CI, 0.21 to 1.02), but risk was increased when IIV3 was given with either PCV (IRR, 3.50; 95% CI, 1.13 to 10.85) or a diphtheria-tetanus-acellular-pertussis (DTaP)-containing vaccine (IRR, 3.50; 95% CI, 1.52 to 8.07).
The maximum estimated absolute excess risk due to concomitant administration of IIV3, PCV, and DTaP-containing vaccines compared with administration on separate days was 30 FS per 100 000 persons vaccinated.CONCLUSIONS: The administration of IIV3 on the same day as either PCV or a DTaP-containing vaccine was associated with a greater risk of FS than when IIV3 was given on a separate day. The absolute risk of postvaccination FS with these vaccine combinations was small.