Immunity Debt for Seasonal Influenza After the COVID‐19 Pandemic and as a Result of Nonpharmaceutical Interventions: An Ecological Analysis and Cohort Study

Abstract Non‐pharmaceutical interventions (NPIs) during the COVID‐19 pandemic significantly reduced influenza transmission. This study explores the hypothesis of “immunity debt” which suggests increased vulnerability to influenza following reduced exposure during the pandemic. World Health Organizat...

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Main Authors: Li Chen, Yuchen Guo, Kim López‐Güell, Jun Ma, Yanhui Dong, Junqing Xie, Daniel Prieto Alhambra
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Advanced Science
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Online Access:https://doi.org/10.1002/advs.202410513
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author Li Chen
Yuchen Guo
Kim López‐Güell
Jun Ma
Yanhui Dong
Junqing Xie
Daniel Prieto Alhambra
author_facet Li Chen
Yuchen Guo
Kim López‐Güell
Jun Ma
Yanhui Dong
Junqing Xie
Daniel Prieto Alhambra
author_sort Li Chen
collection DOAJ
description Abstract Non‐pharmaceutical interventions (NPIs) during the COVID‐19 pandemic significantly reduced influenza transmission. This study explores the hypothesis of “immunity debt” which suggests increased vulnerability to influenza following reduced exposure during the pandemic. World Health Organization aggregated data on influenza from 116 countries and its association with NPI intensity as measured by the COVID‐19 Stringency Index is analyzed. Where individual‐level data available (France, the United Kingdom, Spain, Italy, Belgium, and Romania), the analyses of influenza monthly rates in six European countries (France, the United Kingdom, Spain, Italy, Belgium, and Romania) are replicated. The results indicate globally a 46.3% (95% CI: 15.79–70.78%) reduction in influenza cases during COVID‐19 restrictions in the winter season, followed by a 131.7% (95% CI: 34.95–255.78%) increase in the first postrelaxation winter and a 161.2% (95% CI: 31.88–382.16%) increase in the summer as compared to the predicted level based on historical influenza epidemic trends. In addition, a positive association between the Stringency Index and post‐relaxation influenza surge is observed globally (R2 = 0.14–0.17) and replicated regionally. The findings support the population immunity debt hypothesis for influenza and call for proactive preparations against its consequences in future pandemics.
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spelling doaj-art-b35312d918d44c8ba40f913396b3ffc12025-08-20T03:20:10ZengWileyAdvanced Science2198-38442025-05-011220n/an/a10.1002/advs.202410513Immunity Debt for Seasonal Influenza After the COVID‐19 Pandemic and as a Result of Nonpharmaceutical Interventions: An Ecological Analysis and Cohort StudyLi Chen0Yuchen Guo1Kim López‐Güell2Jun Ma3Yanhui Dong4Junqing Xie5Daniel Prieto Alhambra6Centre for Statistics in Medicine and NIHR Biomedical Research Centre Oxford NDORMS University of Oxford Oxford OX3 7HE UKCentre for Statistics in Medicine and NIHR Biomedical Research Centre Oxford NDORMS University of Oxford Oxford OX3 7HE UKCentre for Statistics in Medicine and NIHR Biomedical Research Centre Oxford NDORMS University of Oxford Oxford OX3 7HE UKInstitute of Child and Adolescent Health School of Public Health Peking University Beijing 100083 ChinaInstitute of Child and Adolescent Health School of Public Health Peking University Beijing 100083 ChinaCentre for Statistics in Medicine and NIHR Biomedical Research Centre Oxford NDORMS University of Oxford Oxford OX3 7HE UKCentre for Statistics in Medicine and NIHR Biomedical Research Centre Oxford NDORMS University of Oxford Oxford OX3 7HE UKAbstract Non‐pharmaceutical interventions (NPIs) during the COVID‐19 pandemic significantly reduced influenza transmission. This study explores the hypothesis of “immunity debt” which suggests increased vulnerability to influenza following reduced exposure during the pandemic. World Health Organization aggregated data on influenza from 116 countries and its association with NPI intensity as measured by the COVID‐19 Stringency Index is analyzed. Where individual‐level data available (France, the United Kingdom, Spain, Italy, Belgium, and Romania), the analyses of influenza monthly rates in six European countries (France, the United Kingdom, Spain, Italy, Belgium, and Romania) are replicated. The results indicate globally a 46.3% (95% CI: 15.79–70.78%) reduction in influenza cases during COVID‐19 restrictions in the winter season, followed by a 131.7% (95% CI: 34.95–255.78%) increase in the first postrelaxation winter and a 161.2% (95% CI: 31.88–382.16%) increase in the summer as compared to the predicted level based on historical influenza epidemic trends. In addition, a positive association between the Stringency Index and post‐relaxation influenza surge is observed globally (R2 = 0.14–0.17) and replicated regionally. The findings support the population immunity debt hypothesis for influenza and call for proactive preparations against its consequences in future pandemics.https://doi.org/10.1002/advs.202410513COVID‐19immunity debtinfluenzanonpharmaceutical interventions
spellingShingle Li Chen
Yuchen Guo
Kim López‐Güell
Jun Ma
Yanhui Dong
Junqing Xie
Daniel Prieto Alhambra
Immunity Debt for Seasonal Influenza After the COVID‐19 Pandemic and as a Result of Nonpharmaceutical Interventions: An Ecological Analysis and Cohort Study
Advanced Science
COVID‐19
immunity debt
influenza
nonpharmaceutical interventions
title Immunity Debt for Seasonal Influenza After the COVID‐19 Pandemic and as a Result of Nonpharmaceutical Interventions: An Ecological Analysis and Cohort Study
title_full Immunity Debt for Seasonal Influenza After the COVID‐19 Pandemic and as a Result of Nonpharmaceutical Interventions: An Ecological Analysis and Cohort Study
title_fullStr Immunity Debt for Seasonal Influenza After the COVID‐19 Pandemic and as a Result of Nonpharmaceutical Interventions: An Ecological Analysis and Cohort Study
title_full_unstemmed Immunity Debt for Seasonal Influenza After the COVID‐19 Pandemic and as a Result of Nonpharmaceutical Interventions: An Ecological Analysis and Cohort Study
title_short Immunity Debt for Seasonal Influenza After the COVID‐19 Pandemic and as a Result of Nonpharmaceutical Interventions: An Ecological Analysis and Cohort Study
title_sort immunity debt for seasonal influenza after the covid 19 pandemic and as a result of nonpharmaceutical interventions an ecological analysis and cohort study
topic COVID‐19
immunity debt
influenza
nonpharmaceutical interventions
url https://doi.org/10.1002/advs.202410513
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