Status epilepticus following vaccination in children aged ≤24 months: A five-year retrospective observational study.

Background: Status epilepticus is associated with significant morbidity and mortality. While vaccine-proximate status epilepticus (VP-SE) has rarely been associated with cases of Dravet syndrome, it is not known whether VP-SE differs clinically from non-vaccine proximate status epilepticus (NVP-SE).

Methods: Medical records of children aged ≤24 months, presenting to one of five Australian tertiary pediatric hospitals with their first episode of status epilepticus from 2013 to 2017 were identified using ICD-coded discharge diagnoses. Vaccination history was obtained from the Australian Immunisation Register. Hospitalization details, subsequent epilepsy diagnosis, and vaccination uptake were compared between VP-SE and NVP-SE cases.

Results: Of 245 first status epilepticus hospitalization with immunization records, 35 (14%) were VP-SE and 21 (60%) followed measles-containing vaccines. Vaccine-proximate status epilepticus cases had a median age of 12.5 months [IQR 7.1-14.73], 23 (66%) were in males, 15 (43%) were febrile status epilepticus and 17 (49%) had an infection confirmed. There were no significant differences in hospitalization duration (P = 0.50) or intensive care unit admission (P = 0.42) between children with VP-SE compared to children with NVP-SE. Children with no history of seizures at their first VP-SE had longer hospitalizations, were more likely to require intensive care unit admission, but were less likely to have a subsequent diagnosis of epilepsy than children with previous seizures at their first VP-SE.

Conclusion: First VP-SE was predominantly associated with a measles-containing vaccine at 12-months of age. Seizure severity was no different between first VP-SE and first NVP-SE. In children with VP-SE, subsequent seizure admissions and epilepsy diagnosis were associated with having seizure prior to their first SE.