Revaccination outcomes of children with vaccine proximate seizures

BackgroundSeizures, whether febrile or afebrile, occurring within 14 days following vaccination can be considered as vaccine proximate seizures (VPSs). While the attributable risk and clinical severity of first febrile VPS is well known, the risk and clinical outcomes of VPS recurrence is less well defined.MethodsWe conducted a retrospective review of revaccination management and outcomes in children who experienced a VPS as their first seizure seen in Australian Specialist Immunisation Clinics between 2013 and 2017. Vaccination outcomes were compared between children who had a VPS as their only seizure (VPS only) and children who had further non-vaccine proximate seizures following their initial VPS (VPS+) prior to review at the clinic.ResultsWe identified 119 children with a VPS as their first seizure, of which 61 (51%) went on to have other seizures (VPS+). Children with VPS+ were more likely to present at a younger age (6.2 vs 12.5 months, P = 0.03), with afebrile seizures (42.6% vs 15.5%, P = 0.002) compared to VPS only children. VPS recurrence on revaccination was uncommon in both groups, but more common in VPS+ children (12.5% vs 2.4%, P = 0.07). Having an epilepsy diagnosis, specifically Dravet syndrome, was associated with VPS recurrence (P < 0.001). Of the four children with Dravet syndrome who had VPS recurrence, all had status epilepticus following revaccination.ConclusionIn children who presented with a single VPS as their only seizure, VPS recurrence on revaccination was uncommon. Children who had multiple non-vaccine proximate seizures following their initial VPS (VPS+) were more likely to present with afebrile VPS, at a younger age and have a VPS recurrence with vaccination. In these children, particularly those aged < 12 months, assessment and investigation for diagnosis of Dravet syndrome should be considered and additional precautions for revaccination undertaken as they are at highest risk of VPS recurrence.