The severity and duration of vaccine-proximate febrile seizures (VP-FSs) are no worse than non–vaccine proximate febrile seizures (NVP-FSs), according to a study in Pediatrics.

Toddler is held by mother while being vaccinated by doctor. KatarzynaBialasiewicz/Thinkstock

Lucy Deng, MBBS, of the University of Sydney and her colleagues investigated 1,022 index febrile seizures in children aged 6 years or less, of which 6% (n = 67) were VP-FSs and 94% (n = 955) were NVP-FSs. Both univariate and multivariate analyses showed no increased risk of severe seizure associated with VP-FSs, compared with NVP-FS. Most of the febrile seizures of either type were brief (15 minutes or less) and had a length of stay of 1 day or less; there also were no differences in 24-hour recurrence. The most common symptom was respiratory, and the rates were similar in each group (62.7% with VP-FS vs. 62.8% with NVP-FS). In keeping with a known 100% increased risk associated with measles vaccination, 84% of VP-FSs were associated with measles-containing vaccines. The majority of the remaining VP-FSs occurred after combination vaccines.

One limitation is that, because these cases were documented in sentinel tertiary pediatric hospitals, the case ascertainment may not be representative. Also, the small proportion of VP-FSs and limited cohort size means the study may not have been powered to detect true differences in prolonged seizures between the groups, Dr. Deng and her colleagues wrote.

“This study confirms that VP-FSs are clinically not any different from NVP-FSs and should be managed the same way,” the researchers concluded.

The authors reported no relevant financial disclosures, although Dr. Deng is supported by the University of Sydney Training Program scholarship, and two other study authors are supported by Australian National Health and Medical Research Council Career Development Fellowships. The study was funded by a grant from the Australian Government Department of Health and the National Health and Medical Research Council.

SOURCE: Deng L et al. Pediatrics. 2019 Apr 19. doi: 10.1542/peds.2018-2120.