Dynamics of parainfluenza virus among hospitalized children with acute respiratory tract infection under two-child policy and COVID-19 pandemic in Hubei Province, China, 2014-2022.

To analyze changes in the detection of parainfluenza virus (PIV) in children hospitalized with acute respiratory tract infection (ARTI) during 2014-2022 in Hubei Province, and explore the impact of the universal two-child policy and the public health measures against COVID-19 epidemic on the prevalence of PIV in China. The study was conducted at the Maternal and Child Health Hospital of Hubei Province. Children aged <18 years with ARTI admitted from January 2014 to June 2022 were enrolled. The infection of PIV was confirmed by the direct immunofluorescence method in nasopharyngeal specimens. Adjusted logistic regression models were used to analyze the influence of the universal two-child policy implementation and public health measurements against COVID-19 on PIV detection. Totally 75 128 inpatients meeting the criteria were enrolled in this study from January 2014 to June 2022 with an overall PIV positive rate of 5.5%. The epidemic seasons of PIV prevalence lagged substantially in 2020. A statistically significant higher positive rate of PIV was observed in 2017-2019 compared to that in 2014-2015 (6.12% vs 2.89%, risk ratio = 2.12, p < 0.001) after the implementation of the universal two-child policy in 2016. A steep decline occurred in PIV positive rate during the COVID-19 epidemic in 2020 (0.92% vs 6.92%, p < 0.001) and it rebounded during the regular epidemic prevention and control period in 2021-2022 (6.35%, p = 0.104). In Hubei Province, the implementation of the universal two-child policy might have led to an increase of PIV prevalence, and public health measures during the COVID-19 epidemic might have influenced the fluctuation in PIV detection since 2020.