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. 2025 Dec 30;13(1):ofaf759.
doi: 10.1093/ofid/ofaf759. eCollection 2026 Jan.

Normalization of Seasonality and Age Distribution of Pediatric RSV Infection Following the Pandemic Disruption in the Netherlands

Neele Rave  1 , Marit E M de Bruijne  1 , Rebecca K Stellato  2 , Michiel A G E Bannier  3 , Daniel M Weinberger  4 , Yvette N Löwensteyn  1 , Joanne G Wildenbeest  1 , Louis J Bont  1   5 ; Surveillance of Pediatric REspiratory Admissions in Dutch hospitals (SPREAD) Study Group
Collaborators, Affiliations

Normalization of Seasonality and Age Distribution of Pediatric RSV Infection Following the Pandemic Disruption in the Netherlands

Neele Rave et al. Open Forum Infect Dis. .

Abstract

Background: The COVID-19 pandemic caused a global disruption in respiratory syncytial virus (RSV) epidemiology. However, data on RSV epidemiology in the postpandemic period remain limited. We analyzed shifts in RSV seasonality, age distribution, and disease severity among RSV-positive children in the Netherlands before, during, and after the pandemic.

Methods: Between May 2021 and April 2024, children under two years of age, admitted with RSV to 47 Dutch hospitals were included in a prospective surveillance study. We compared demographic and clinical characteristics of RSV-positive patients with data from the pre-COVID period (2018-2020), the COVID period and the post-COVID period (2022-2024).

Results: A total of 8457 RSV-positive cases were included, with detailed data collected from 2708 patients (13 hospitals). Following an unusual off-season shift and a period of endemic circulation, RSV seasonality has reverted to its typical prepandemic winter pattern. The median age at admission increased from 2.2 months (interquartile range [IQR]: 1.1-5.6) in the prepandemic period to 4.9 months (IQR 1.8-11.4, P < .05) during the summer outbreak (2021). This subsequently returned to prepandemic median age in the winter of 2023/2024 (2.7 months, IQR 1.3-8.0, not significant). We observed no differences in the prevalence of preterm birth or comorbidities among RSV-positive children before, during or after the COVID pandemic.

Conclusions: The COVID-19 pandemic profoundly disrupted RSV epidemiology. This prospective study demonstrates a rapid re-establishment of prepandemic patterns, including a return toward the typical age distribution during early childhood.

Keywords: epidemiology; immunization; post-COVID-19; respiratory syncytial virus; seasonality.

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Conflict of interest statement

Potential conflicts of interest. L. J. B. has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. U. M. C. U. has received major funding (greater than €100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, Janssen Pharmaceuticals, the Bill & Melinda Gates Foundation, Nutricia (Danone), and MeMed Diagnostics. U. M. C. U. has received major cash or in-kind funding as part of the public–private partnership Innovative Medicines Initiative (IMI)—funded RESCEU (Respiratory Syncytial Virus Consortium in Europe) project from GlaxoSmithKline, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi. U. M. C. U. has received major funding by Julius Clinical for participating in the International Network For Optimal Resistance Monitoring of RSV study sponsored by MedImmune. U. M. C. U. has received minor funding for participation in trials by Regeneron Pharmaceuticals and Janssen from 2015 to 2017 (total annual estimate less than €20 000). U. M. C. U. received minor funding for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavarian Nordic, mAbxience, Novavax, Pfizer, and Janssen (total annual estimate less than €20 000). L. J. B. is the founding chair of the Respiratory Syncytial Virus Foundation (ReSViNET) Foundation. D. M. W. has been PI on research grants from Pfizer, Merck, and GSK to Yale University and has received personal consulting fees from Pfizer, Merck, and GSK. J. G. W. has been an investigator for clinical trials sponsored by pharmaceutical companies including AstraZeneca, Merck, Pfizer, Sanofi, and Janssen. All funds have been paid to UMCU. J. G. W. participated in advisory boards of Janssen and Sanofi and was a speaker at Sanofi and MSD sponsored symposia with fees paid to UMCU. All other authors report no potential conflicts.

Figures

Figure 1.
Figure 1.
Weekly number of RSV-positive cases in children under 2 years of age across different epidemic seasons in the Netherlands from May 2021 to April 2024. (A) Comparison of RSV seasonality between pandemic and postpandemic seasons, based on data from 47 hospitals (B) RSV seasonality patterns before, during, and after the COVID-19 pandemic, based on data from 13 hospitals.
Figure 2.
Figure 2.
Age distribution of RSV-positive children under 2 years of age admitted to the hospital per group from October 2018 until April 2024. The x axis represents distinct time period before, during, and after the COVID-19 pandemic. The width of each violin shape at each age level (in months) reflects the relative frequency of RSV-positive cases at that age. The boxplots within each violin display the median age, the interquartile range, and outliers of RSV-positive cases for each time period.
See this image and copyright information in PMC

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