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Eur J Clin Microbiol Infect Dis
. 2025 Oct 13.
doi: 10.1007/s10096-025-05249-8. Online ahead of print. Shifts in epidemic patterns and age dynamics of RSV, IFV, and SARS-CoV-2 in Chinese children following COVID-19 non-pharmaceutical intervention relaxation, 2017 - 2024
Yiguo Zhou # 1 2 , Jian-Bo Xia # 3 , Meimei Luo # 4 , Wan-Xue Zhang 5 , Shan-Shan Zhang 5 , Le Ao 5 , Han Yang 5 , Qin-Yi Ma 5 , Juan Du 2 , Yu-Ting Wang 5 , Ninghua Huang 2 , Xing-Wen Hu 6 , Fuqiang Cui 7 8 9 10 , Qing-Bin Lu 11 12 13 14
Affiliations
Background: Following the nationwide relaxation of non-pharmaceutical interventions (NPIs) in December 2022 in China, there was considerable uncertainty regarding the resurgence and interaction patterns of major respiratory syncytial virus (RSV), influenza virus (IFV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We hypothesized that this post-NPI era would experience an unusual resurgence of traditional respiratory viruses with altered seasonality and age distribution, alongside distinct epidemic patterns of SARS-CoV-2.
Methods: This retrospective observational study analyzed comprehensive surveillance data of RSV, IFV, and SARS-CoV-2 from pediatric acute respiratory tract infection (ARTI) cases at a major maternal and child health hospital in Hubei Province, China, spanning September 2017 to August 2024. We examined temporal trends across pre-pandemic, pandemic, and post-NPI periods, age distribution shifts across four defined age groups, and coinfection patterns.
Results: A large dataset of 105,264 RSV, 177,754 IFV and 23,090 SARS-CoV-2 test records were analyzed. Following the lifting of NPIs, delayed RSV and IFV outbreaks occurred in 2022-2023 season with unusual seasonality (e.g., RSV peaking atypically in April). In the 2023-2024 season, a partial return to traditional seasonality was observed, though IFV exhibited an unprecedentedly high peak. Significant age distribution shifts occurred, with RSV infections increasing markedly in the 3 - 6 years age group and IFV infections surging in the 6 - 14 years age group during 2023, largely consistent with an immunity debt phenomenon. SARS-CoV-2 outbreaks consistently followed the peaks of IFV and RSV, showing distinct spring and summer epidemic patterns, particularly affecting young children. Coinfections of RSV and IFV remained consistently rare (about 1%).
Conclusions: The post-NPI era in China brought profound shifts in pediatric respiratory virus epidemiology, characterized by altered seasonality and age distribution for RSV and IFV, and a distinct sequential pattern for SARS-CoV-2. These findings underscore the impact of NPIs on viral dynamics and highlight the concept of immunity debt. Our study provides crucial insights for adaptive public health strategies, emphasizing the need for continued, integrated surveillance and tailored interventions to address the evolving characteristics of these key respiratory pathogens.
Keywords: Acute respiratory tract infection; Epidemiology; Influenza; Post-pandemic seasonality; Respiratory syncytial virus; SARS-CoV-2.
. 2025 Oct 13.
doi: 10.1007/s10096-025-05249-8. Online ahead of print. Shifts in epidemic patterns and age dynamics of RSV, IFV, and SARS-CoV-2 in Chinese children following COVID-19 non-pharmaceutical intervention relaxation, 2017 - 2024
Yiguo Zhou # 1 2 , Jian-Bo Xia # 3 , Meimei Luo # 4 , Wan-Xue Zhang 5 , Shan-Shan Zhang 5 , Le Ao 5 , Han Yang 5 , Qin-Yi Ma 5 , Juan Du 2 , Yu-Ting Wang 5 , Ninghua Huang 2 , Xing-Wen Hu 6 , Fuqiang Cui 7 8 9 10 , Qing-Bin Lu 11 12 13 14
Affiliations
- PMID: 41081990
- DOI: 10.1007/s10096-025-05249-8
Background: Following the nationwide relaxation of non-pharmaceutical interventions (NPIs) in December 2022 in China, there was considerable uncertainty regarding the resurgence and interaction patterns of major respiratory syncytial virus (RSV), influenza virus (IFV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We hypothesized that this post-NPI era would experience an unusual resurgence of traditional respiratory viruses with altered seasonality and age distribution, alongside distinct epidemic patterns of SARS-CoV-2.
Methods: This retrospective observational study analyzed comprehensive surveillance data of RSV, IFV, and SARS-CoV-2 from pediatric acute respiratory tract infection (ARTI) cases at a major maternal and child health hospital in Hubei Province, China, spanning September 2017 to August 2024. We examined temporal trends across pre-pandemic, pandemic, and post-NPI periods, age distribution shifts across four defined age groups, and coinfection patterns.
Results: A large dataset of 105,264 RSV, 177,754 IFV and 23,090 SARS-CoV-2 test records were analyzed. Following the lifting of NPIs, delayed RSV and IFV outbreaks occurred in 2022-2023 season with unusual seasonality (e.g., RSV peaking atypically in April). In the 2023-2024 season, a partial return to traditional seasonality was observed, though IFV exhibited an unprecedentedly high peak. Significant age distribution shifts occurred, with RSV infections increasing markedly in the 3 - 6 years age group and IFV infections surging in the 6 - 14 years age group during 2023, largely consistent with an immunity debt phenomenon. SARS-CoV-2 outbreaks consistently followed the peaks of IFV and RSV, showing distinct spring and summer epidemic patterns, particularly affecting young children. Coinfections of RSV and IFV remained consistently rare (about 1%).
Conclusions: The post-NPI era in China brought profound shifts in pediatric respiratory virus epidemiology, characterized by altered seasonality and age distribution for RSV and IFV, and a distinct sequential pattern for SARS-CoV-2. These findings underscore the impact of NPIs on viral dynamics and highlight the concept of immunity debt. Our study provides crucial insights for adaptive public health strategies, emphasizing the need for continued, integrated surveillance and tailored interventions to address the evolving characteristics of these key respiratory pathogens.
Keywords: Acute respiratory tract infection; Epidemiology; Influenza; Post-pandemic seasonality; Respiratory syncytial virus; SARS-CoV-2.