To define the incidence and characteristics of influenza-associated neurologic complications in a cohort of children hospitalized at a tertiary care pediatric hospital with laboratory-confirmed influenza, and to identify associated clinical, epidemiologic, and virologic factors.
Historical cohort study of children 0.5-18.0 years-old hospitalized between 2010-2017 with laboratory-confirmed influenza. Children with immune compromise or a positive test due to recent receipt of live virus vaccine or recently resolved illness were excluded. Influenza-associated neurologic complications were defined as new-onset neurologic signs/symptoms during acute influenza illness without another clear etiology.
At least one influenza-associated neurologic complication was identified in 10.8% (95% CI 9.1-12.6%, n=131 of 1,217) of hospitalizations with laboratory-confirmed influenza. Seizures (n=97) and encephalopathy (n=44) were the most commonly identified influenza-associated neurologic complication, although an additional 20 hospitalizations had other influenza-associated neurologic complications. Hospitalizations with influenza-associated neurologic complications were similar in age and influenza type (A/B) to those without. Children with a pre-existing neurologic diagnosis (n=326) had a higher proportion of influenza-associated neurologic complications compared with those without (22.7% vs 6.4%, p<0.001). Presence of a pre-existing neurologic diagnosis (aOR 4.6, P < .001), lack of seasonal influenza vaccination (aOR 1.6, p=0.020), and age ≤5 years (aOR 1.6, p=0.017) were independently associated with influenza-associated neurologic complications.
Influenza-associated neurologic complications are common in children hospitalized with influenza, particularly those with pre-existing neurologic diagnoses. A better understanding of the epidemiology and factors associated with influenza-associated neurologic complications will direct future investigation into potential neuropathologic mechanisms and mitigating strategies. Vaccination is recommended and may help prevent influenza-associated neurologic complications in children.

Copyright © 2021. Published by Elsevier Inc.