The Epidemiology and Burden of Human Parainfluenza Virus Hospitalizations in U.S. Children.

Background: Human parainfluenza viruses (PIV) are a major cause of acute respiratory infection (ARI) leading to hospitalization in young children. In order to quantify the burden of PIV hospitalizations and to evaluate the characteristics of children hospitalized with PIV by virus type, we used data from the New Vaccine Surveillance Network (NVSN), a multicenter, active, prospective population-based surveillance network, enrolling children hospitalized for ARI (defined as fever and/or respiratory symptoms) at 7 U.S. children's hospitals.

Methods: The study period included December 1, 2016 through March 31, 2020. Data captured included demographic characteristics, clinical presentation, underlying medical conditions, discharge diagnoses, and virus detection by RT-PCR. Linear and logistic regression were used to compare descriptive and clinical characteristics among children. Population-based PIV-associated hospitalization rates were calculated by age group and PIV-type.

Results: Of the 16,791 enrolled children with PIV virologic testing, 10,488 had only one respiratory virus detected, among whom 702 (7%) had positive testing for PIV without a co-detected virus (mean age [SD], 2.2 [3.2] years). Of these 702 children, 340 (48%) had underlying comorbidities, 139 (20%) had a history of prematurity, 121 (17%) were admitted to the ICU, and 23 (3%) required intubation. Overall, PIV hospitalization rates were highest in children aged 0-5 months (1.91 hospitalizations per 1,000 children per year [95% CI, 1.61-2.23], with PIV-3 contributing to the highest rates in that age group, followed by PIV-1 and PIV-4: 1.08 [0.84-1.21], 0.42 [0.28-0.58] and 0.25 [0.15-0.37] per 1,000 children per year, respectively. Seasonal distribution of PIV-associated hospitalizations varied by type.

Conclusions: PIV infection was associated with a substantial number of ARI hospitalizations in children aged 0-5 months. Results suggest that future PIV prevention strategies in the US that focus on younger children and protection against PIV-3, PIV-1, and PIV-4 might have the greatest impact on reducing PIV hospitalization burden.