Analysis of the Epidemiological Characteristics of Respiratory Syncytial Virus Among Inpatients in the Neonatal Department of a Tertiary Hospital in Taiyuan City Before and After the COVID-19 Pandemic

Objective To retrospectively analyze the epidemiological characteristics of respiratory syncytial virus （RSV） infection in hospitalized neonates before and after the COVID-19 pandemic, to provide clinical evidence for the prevention and treatment of RSV-related diseases.Methods This study was designed as a retrospective cross-sectional analysis. A total of 1,237 neonates diagnosed with infectious pneumonia who underwent respiratory virus etiological testing in the Neonatal Ward of Shanxi Children's Hospital between January 2019 and December 2024 were included as study participants. Among them, infants with positive respiratory syncytial virus (RSV) test results were specifically selected for further analysis. The children were categorized based on their year of admission into three groups: the pre-pandemic group (2019, n = 163), the mid-pandemic group (2020–2022, n = 496), and the post-pandemic group (2023–2024, n = 578). Reflecting the temporal phases before, during, and after the pandemic, each group was further classified according to seasonal patterns defined by the climatic characteristics of Taiyuan City—spring (March, April, and May; n = 10, 90, and 179), summer (June, July, and August; n = 9, 71, and 90), autumn (September, October, and November; n = 80, 155, and 74), and winter (December, January, and February; n = 64, 180, and 235). Additionally, participants were stratified by sex into male (n = 662) and female (n = 575) groups. With regard to age at onset, children were classified into the early neonatal period (age ≤7 days, n = 116) and the late neonatal period (7 days < age ≤28 days, n = 1121). The chi-square test or Fisher's exact test was used for comparisons between two or three groups, and the Bonferroni correction was applied for pairwise comparisons among three groups.Results The overall respiratory syncytial virus (RSV) detection rate during the study period was 26.5% (328/1,237). From 2019 to 2024, the highest RSV detection rate was observed in 2024 [34.8% (120/328)] and the lowest in 2022 [3.8% (3/80)]. The post-epidemic RSV detection rate [32.4% (187/578)] was significantly higher than both the pre-epidemic [21.5% (35/163)] and epidemic-period rates [21.4% (106/496)], with statistically significant differences (Bonferroni-corrected: P = 0.007; P < 0.001). Seasonal distribution analysis showed that RSV detection predominantly occurred in winter and spring in 2019, 2023, and 2024; in autumn and winter in 2020 and 2021; and primarily in winter in 2022. In spring, a statistically significant difference in RSV detection rates across epidemic phases was observed (χ² = 29.79, P < 0.001), with the post-epidemic group exhibiting a significantly higher detection rate than the epidemic group (Bonferroni-corrected: P < 0.001). In autumn, the difference in RSV detection rates was also statistically significant (χ² = 9.38, P = 0.009), with the mid-epidemic period showing a higher detection rate compared to the early epidemic period (Bonferroni-corrected: P = 0.016). No statistically significant differences were found in RSV detection rates between summer and winter (χ² = 2.87, P = 0.238; χ² = 0.781, P = 0.781). Among males, the post-epidemic RSV detection rate [36.0% (109/303)] was significantly higher than both pre-epidemic [20.2% (19/94)] and epidemic-period rates [19.6% (52/265)] (Bonferroni-corrected: P=<0.001; P=<0.001). Additionally, the RSV detection rate was significantly higher in late newborns compared to early newborns [28.4% (318/1,121) vs. 8.6% (10/116), χ² = 21.03, P < 0.001].Conclusion The RSV detection rate among hospitalized neonates with infectious pneumonia fluctuated between 2019 and 2024, showing a notable increase following the pandemic. This rise was particularly evident in spring and among male infants, while a decline was observed in autumn. RSV-positive cases were predominantly identified in late neonates, indicating a higher susceptibility during the later neonatal period.