TY - JOUR
T1 - Shifts in seasonal influenza patterns in Australia during and after COVID-19
T2 - A comprehensive analysis
AU - Lu, Cynthia
AU - Barr, Ian G
AU - Lambert, Stephen
AU - Mengersen, Kerrie
AU - Wang, Liping
AU - Yang, Weizhong
AU - Li, Zhongjie
AU - Vardoulakis, Sotiris
AU - Bambrick, Hilary
AU - Hu, Wenbiao
N1 - Funding Information:
This research was funded by the National Foundation for Australia-China Relations (Grant No. 220011), the Australian Department of Foreign Affairs and Trade (DFAT).
Publisher Copyright:
© 2024 The Author(s)
PY - 2025/1
Y1 - 2025/1
N2 - BACKGROUND: During the COVID-19 pandemic, seasonal influenza virus circulation was heavily suppressed worldwide. In Australia, since the virus re-emerged in 2022, shifts in seasonal influenza patterns have been observed. Both the 2022 and 2023 seasons started earlier than pre-pandemic norms and were categorised as moderate to severe, highlighting the renewed importance of prevention strategies for seasonal influenza.METHODS: We analysed influenza notification data from the Australian National Notifiable Diseases Surveillance System (2012-2022) and virological surveillance data from the FluNet database (2012-2023). Using generalised additive models, we compared predicted weekly influenza case counts during 2020-2022 with observed counts. Epidemic weeks were detected using a negative binomial threshold, and epidemic onset was estimated with a Bayesian Poisson count detection algorithm. Trends in epidemic magnitude and onset timing across influenza virus types and subtypes were compared for pre-, during, and post-COVID-19 periods.RESULTS: Seasonal influenza activity was nearly absent in 2020 and 2021 but rebounded significantly in 2022 and 2023. Epidemic detection confirmed suppressed seasonal influenza circulation during the pandemic. While influenza A subtypes returned to pre-pandemic onset timings in 2022, influenza B exhibited a significantly delayed onset. The 2022 and 2023 seasons were moderate to severe, with earlier-than-average season starts, underscoring the ongoing changes in influenza dynamics post-pandemic.CONCLUSIONS: This study provided a detailed analysis of the disruptions and subsequent shifts in seasonal influenza patterns in Australia during and after the COVID-19 pandemic. The rapid resurgence of influenza activity in 2022 and 2023, combined with altered onset timings, highlights the importance of ongoing surveillance and adaptive forecasting models to address the evolving complexity of influenza epidemiology in the post-pandemic era.
AB - BACKGROUND: During the COVID-19 pandemic, seasonal influenza virus circulation was heavily suppressed worldwide. In Australia, since the virus re-emerged in 2022, shifts in seasonal influenza patterns have been observed. Both the 2022 and 2023 seasons started earlier than pre-pandemic norms and were categorised as moderate to severe, highlighting the renewed importance of prevention strategies for seasonal influenza.METHODS: We analysed influenza notification data from the Australian National Notifiable Diseases Surveillance System (2012-2022) and virological surveillance data from the FluNet database (2012-2023). Using generalised additive models, we compared predicted weekly influenza case counts during 2020-2022 with observed counts. Epidemic weeks were detected using a negative binomial threshold, and epidemic onset was estimated with a Bayesian Poisson count detection algorithm. Trends in epidemic magnitude and onset timing across influenza virus types and subtypes were compared for pre-, during, and post-COVID-19 periods.RESULTS: Seasonal influenza activity was nearly absent in 2020 and 2021 but rebounded significantly in 2022 and 2023. Epidemic detection confirmed suppressed seasonal influenza circulation during the pandemic. While influenza A subtypes returned to pre-pandemic onset timings in 2022, influenza B exhibited a significantly delayed onset. The 2022 and 2023 seasons were moderate to severe, with earlier-than-average season starts, underscoring the ongoing changes in influenza dynamics post-pandemic.CONCLUSIONS: This study provided a detailed analysis of the disruptions and subsequent shifts in seasonal influenza patterns in Australia during and after the COVID-19 pandemic. The rapid resurgence of influenza activity in 2022 and 2023, combined with altered onset timings, highlights the importance of ongoing surveillance and adaptive forecasting models to address the evolving complexity of influenza epidemiology in the post-pandemic era.
KW - Humans
KW - Influenza, Human/epidemiology
KW - Australia/epidemiology
KW - COVID-19/epidemiology
KW - Seasons
KW - SARS-CoV-2
KW - Bayes Theorem
KW - Pandemics
KW - Influenza A virus/isolation & purification
KW - Influenza B virus/isolation & purification
UR - http://www.scopus.com/inward/record.url?scp=85212542186&partnerID=8YFLogxK
U2 - 10.1016/j.jiph.2024.102620
DO - 10.1016/j.jiph.2024.102620
M3 - Article
C2 - 39708760
AN - SCOPUS:85212542186
SN - 1876-0341
VL - 18
SP - 1
EP - 11
JO - Journal of Infection and Public Health
JF - Journal of Infection and Public Health
IS - 1
M1 - 102620
ER -
