Impact of infections on the incidence of acute inflammatory demyelinating polyneuropathy in children.

Objectives: Acute inflammatory demyelinating polyneuropathy (AIDP) is the leading cause of acute flaccid paralysis in children and hypothesized to be triggered by antecedent infection. We sought to determine the association between AIDP and commonly acquired community infections in children. We utilized the reduction in these infections due to measures during coronavirus disease 2019 (COVID-19) to serve as a natural experiment and determine their contribution to AIDP. Methods: This cross-sectional study used administrative and billing data from children's hospitals contributing to the Pediatric Health Information System. We included hospitalizations of children with a diagnosis of AIDP from (January 2017 through February 2021). Encounters for infection- (including respiratory, gastrointestinal, and COVID-19) related diagnoses were measured as a marker of community incidence. Results: A total of 1111 index encounters for AIDP were included. Pre-COVID-19, AIDP was not associated with respiratory or gastrointestinal infections, specifically, influenza or campylobacter. During the COVID-19 period from March 2020 to February 2021, respiratory, gastrointestinal, and influenza infections decreased compared to expected (for the same time of year pre-COVID-19) by 59.6%-90.1%, 51.5%-68.9%, and 54.5%-97.9%, respectively. In contrast, AIDP hospitalizations and all hospitalizations only decreased by 11.5%-39.3% and 14.2%-25%, respectively. COVID-19 was not positively associated with AIDP overall or at individual hospitals. Interpretation: Common community-acquired infections including COVID-19 were not strongly associated with hospitalizations for AIDP in children. AIDP persisted despite the dramatic reduction in infection-related encounters during the pandemic. These results suggest that recent antecedent community-acquired infections were not the primary driver of AIDP and that alternative triggers should be explored.