October 26, 2019
2 min read

Febrile seizures following vaccination do not affect development, behavior

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Photo of Lucy Deng
Lucy Deng

NEW ORLEANS — Children who experience febrile seizures following vaccination have similar developmental and behavioral outcomes compared with both children who had febrile seizures that did not occur after vaccination and those who never had a febrile seizure, according to research presented at the AAP National Conference & Exhibition.

Lucy Deng, MBBS, a pediatrician at the National Center for Immunization Research and Surveillance in Sydney, Australia, said adverse events following vaccination — especially neurological events like febrile seizures — can cause anxiety about the safety of vaccines, affect parents’ confidence in vaccination and reduce vaccination uptake.

According to Deng and colleagues, between 3% and 5% of children aged younger than 6 years experience febrile seizures, with most cases occurring in the second year of life. Of these cases, only a small number occur following vaccination. During this time, they said, many children receive their first dose of a measles-containing vaccine.

“Prior to this study, we knew that febrile seizures following other causes of a febrile illness, such as a viral infection, do not impact children's development or behavior,” Deng told Infectious Diseases in Children. “We can now reassure parents that this is also the case for febrile seizures following vaccination. We have previously shown that the severity of febrile seizures following vaccination is no different from that of other febrile seizures. This longer term, prospective, follow-up study shows that children have normal development and behavior 12 to 24 months following their initial febrile seizure following vaccination.”

Deng and colleagues compared the developmental outcomes of children who had vaccine-proximate febrile seizures (VP-FS) with those who had non-vaccine-proximate febrile seizures (NVP-FS) and those who have never had a febrile seizure (control) at four tertiary pediatric hospitals. Young children who had their first febrile seizure before age 30 months were included in the research. All seizures occurred between May 2013 and April 2016.

A VP-FS was defined as a febrile seizure occurring 0 to 2 days after administration of an inactivated vaccine, 5 to 14 days after receiving a live-attenuated vaccine or 0 to 14 days after receiving a combination of both inactivated and live-attenuated vaccines.

The researchers then assessed children’s development 12 to 24 months after their initial febrile seizure and at aged 12 to 42 months for control children using the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). Parents rated their child’s behaviour and executive functioning using the preschool version of the Behaviour Rating Inventory of Executive Function and the Child Behaviour Checklist, preschool.

Deng and colleagues identified no significant differences in cognitive function between children with VP-FS (n = 62), NVP-FS (n = 70) and those in the control group (n = 90). Furthermore, the researchers did not identify significant differences for all other developmental measures or an increased risk for borderline or significant developmental impairment compared with controls. There also were no clinically significant behavioral differences in children with VP-FS or NVP-FS compared with controls.

According to Deng and colleagues, the only predictor of cognitive functioning in children with VP-FS or NVP-FS was maternal education or socioeconomic status (P = .04).

“This study provides evidence for pediatricians to confidently reassure parents that there are no behavioral or developmental concerns for children who've had a febrile seizure following vaccination,” Deng said. “These events should be managed like any other febrile seizure. Pediatricians should continue to recommend vaccinations in these children.” – by Katherine Bortz


Deng L, et al. Febrile seizures following vaccination do not impact on children’s development on behavior. Presented at: AAP National Conference & Exhibition; Oct. 25-29, 2019; New Orleans.

Disclosure: Deng reports receiving a grant from the Australian National Health and Medical Research Council and  scholarship funds from the University of Sydney.