Febrile Seizure Risk Slightly Higher With Vaccine Combinations in Kids

By Will Boggs MD

NEW YORK (Reuters Health) - The risk of febrile seizures in children increases slightly when trivalent inactivated influenza vaccine (IIV3) is given in combination with pneumococcal conjugate vaccine (PCV) or a diphtheria-tetanus-acellular-pertussis (DTaP)-containing vaccine, according to a new study.

"The results of this study have already been presented to the Advisory Committee on Immunization Practices, and the committee decided that the small absolute risk of febrile seizure following these vaccines did not warrant any change in the recommended use of these vaccines," said Dr. Jonathan Duffy from the U.S. Centers for Disease Control and Prevention in Atlanta, Georgia.

"We are glad that this report has been published so that providers may review the findings for themselves. We hope this information will help providers when they discuss the benefits and risks of vaccination with parents," he told Reuters Health by email.

Previous studies have found an increased risk of febrile seizures for several days after certain childhood vaccines, and one epidemiologic investigation found an independent risk of febrile seizures when IIV3 was given at the same time as PCV.

Dr. Duffy and colleagues used data from the Vaccine Safety Datalink to determine whether 10 other vaccines given concomitantly with IIV3 affected the risk of febrile seizures after vaccination.

They used the self-controlled risk-interval method to compare the incidence of febrile seizures during the risk interval (0-1 days postvaccination) to that during the control interval (14-20 days postvaccination).

None of the IIV3 formulations given alone were associated with and increased risk of febrile seizures among children aged 6 through 23 months, the team reports in Pediatrics, online June 6.

In contrast, the risk of febrile seizures was increased when IIV3 was given with either PCV or a DTaP-containing vaccine or when all three were given together.

The maximum excess risk of febrile seizures was 30 per 100,000 persons vaccinated when all three vaccines were given on the same day versus administration on separate days.

The excess risk of receiving IIV3 with a DTaP-containing vaccine was 24 per 100,000 persons vaccinated and was 16 per 100,000 persons vaccinated for IIV3 given with PCV.

"Parents should keep in mind that the vaccines recommended for children in the United States protect against serious infections that can sometimes require hospitalization or cause death," Dr. Duffy concluded. "While some vaccines can cause a child to have a fever or increase the child's chance of having a febrile seizure in the first day or two after receiving the vaccine, febrile seizures do not cause any long term harm to a child. The benefits of vaccination are much greater and longer lasting than the small risk of a child having a febrile seizure in the few days after getting a vaccine."

"This means for the average pediatrician, who may care for 1000 children younger than 5 including 3 to 500 between 6 and 24 months of age annually, one could expect to see at most 1 child who experiences a febrile seizure every 5 to 10 years due to administration of these vaccines together in the first 2 years of life," write Dr. Mark H. Sawyer from the University of California, San Diego, and colleagues in a related editorial.

"This would be in addition to the 30 to 75 patients in each birth year cohort in a practice that would experience a febrile seizure from other causes given the background rate of 2% to 5%," they note.

"The increased risk of febrile seizures related to the combined use of these 3 routine pediatric vaccines is trivial and the benefits of combined vaccination outweigh the risk of combined vaccination," Dr. Sawyer told Reuters Health by email. "The benefit, of course, is protection from disease as early as possible."

"Vaccines remain one of the most effective and cost-effective health interventions we have and if we let our coverage rates drop we will see outbreaks of diseases that have largely been eliminated through vaccination," Dr. Sawyer concluded.

SOURCE: https://bit.ly/1UAcCGP and https://bit.ly/1rd3sZu

Pediatrics 2016.

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