Severity Scale of Influenza and Acute Respiratory Illness Hospitalizations to Support Viral Genomic Surveillance: A Global Influenza Hospital Surveillance Network Pilot Study

Bronke Boudewijns¹, Saverio Caini¹, Marco Del Riccio^{1

2}, Marta C Nunes^{3

4}, Sandra S Chaves⁵, Melissa K Andrew^{6

7}, Justin R Ortiz⁸, Oana Săndulescu^{9

10}, Joseph S Bresee¹¹, Elena Burtseva¹², Daouda Coulibaly¹³, Daria M Danilenko¹⁴, Kirill Stolyarov¹⁴, Anca C Drăgănescu^{9

15}, Mine Durusu Tanriover^{16

17}, Heloisa I G Giamberardino¹⁸, Parvaiz A Koul¹⁹, F Xavier Lopez-Labrador^{20

21

22}, Shelly A McNeil^{6

7}, Ainara Mira-Iglesias^{22

23}, Alejandro Orrico-Sanchez^{22

23

24}, Nancy A Otieno²⁵, Jorim Ayugi²⁵, Sonia M Raboni²⁶, Peter Spreeuwenberg¹

Affiliations

¹ Netherlands Institute for Health Services Research (Nivel), Utrecht, the Netherlands.
² Department of Health Sciences, University of Florence, Florence, Italy.
³ Center of Excellence in Respiratory Pathogens (CERP), Hospices Civils de Lyon (HCL) and Centre International de Recherche en Infectiologie (CIRI), Équipe Santé Publique, Épidémiologie et Écologie Évolutive des Maladies Infectieuses (PHE3ID), Inserm U1111, CNRS UMR5308, ENS de Lyon, Université Claude Bernard Lyon 1, Lyon, France.
⁴ South African Medical Research Council, Vaccines and Infectious Diseases Analytics Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
⁵ Foundation for Influenza Epidemiology, Fondation de France, Paris, France.
⁶ Department of Medicine, Dalhousie University, Halifax, Canada.
⁷ Canadian Center for Vaccinology, Dalhousie University, Halifax, Canada.
⁸ Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA.
⁹ Department of Infectious Diseases I, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
¹⁰ National Institute for Infectious Diseases "Prof.Dr. Matei Balș", Bucharest, Romania.
¹¹ Task Force for Global Health, Decatur, Georgia, USA.
¹² Gamaleya Federal Research Center for Epidemiology and Microbiology, Ministry of Health of Russian Federation, Moscow, Russia.
¹³ Epidémiologie - Santé Publique, Institut National d'Hygiène Publique (INHP), Abidjan, Côte d'Ivoire.
¹⁴ Smorodintsev Research Institute of Influenza, St. Petersburg, Russia.
¹⁵ Department of Pediatrics, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
¹⁶ Hacettepe University Vaccine Institute, Ankara, Türkiye.
¹⁷ Turkish Society of Internal Medicine, Ankara, Türkiye.
¹⁸ Epidemiology and Infection Control/Immunization Department, Pequeno Principe Hospital, Curitiba, Brazil.
¹⁹ Sheri Kashmir Institute of Medical Sciences, Srinagar, India.
²⁰ Virology Laboratory, FISABIO-Public Health, Generalitat Valenciana, Valencia, Spain.
²¹ Department of Microbiology and Ecology, University of Valencia Medical School, Valencia, Spain.
²² CIBERESP Network Center for Epidemiology and Public Health, Instituto de Salud Carlos III, Madrid, Spain.
²³ Vaccine Research Department, Fisabio-Public Health, Valencia, Spain.
²⁴ Universidad Católica de Valencia San Vicente Mártir, Valencia, Spain.
²⁵ Kenya Medical Research Institute (KEMRI), Nairobi, Kenya.
²⁶ Molecular Biology/Microbiology Research Laboratory, Universidade Federal Do Paraná, Curitiba, Brazil.

PMID: 40045898
PMCID: PMC11883289
DOI: 10.1111/irv.70085

Severity Scale of Influenza and Acute Respiratory Illness Hospitalizations to Support Viral Genomic Surveillance: A Global Influenza Hospital Surveillance Network Pilot Study

Bronke Boudewijns et al. Influenza Other Respir Viruses. 2025 Mar.

. 2025 Mar;19(3):e70085.

doi: 10.1111/irv.70085.

Authors

Affiliations

¹ Netherlands Institute for Health Services Research (Nivel), Utrecht, the Netherlands.
² Department of Health Sciences, University of Florence, Florence, Italy.
³ Center of Excellence in Respiratory Pathogens (CERP), Hospices Civils de Lyon (HCL) and Centre International de Recherche en Infectiologie (CIRI), Équipe Santé Publique, Épidémiologie et Écologie Évolutive des Maladies Infectieuses (PHE3ID), Inserm U1111, CNRS UMR5308, ENS de Lyon, Université Claude Bernard Lyon 1, Lyon, France.
⁴ South African Medical Research Council, Vaccines and Infectious Diseases Analytics Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
⁵ Foundation for Influenza Epidemiology, Fondation de France, Paris, France.
⁶ Department of Medicine, Dalhousie University, Halifax, Canada.
⁷ Canadian Center for Vaccinology, Dalhousie University, Halifax, Canada.
⁸ Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA.
⁹ Department of Infectious Diseases I, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
¹⁰ National Institute for Infectious Diseases "Prof.Dr. Matei Balș", Bucharest, Romania.
¹¹ Task Force for Global Health, Decatur, Georgia, USA.
¹² Gamaleya Federal Research Center for Epidemiology and Microbiology, Ministry of Health of Russian Federation, Moscow, Russia.
¹³ Epidémiologie - Santé Publique, Institut National d'Hygiène Publique (INHP), Abidjan, Côte d'Ivoire.
¹⁴ Smorodintsev Research Institute of Influenza, St. Petersburg, Russia.
¹⁵ Department of Pediatrics, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
¹⁶ Hacettepe University Vaccine Institute, Ankara, Türkiye.
¹⁷ Turkish Society of Internal Medicine, Ankara, Türkiye.
¹⁸ Epidemiology and Infection Control/Immunization Department, Pequeno Principe Hospital, Curitiba, Brazil.
¹⁹ Sheri Kashmir Institute of Medical Sciences, Srinagar, India.
²⁰ Virology Laboratory, FISABIO-Public Health, Generalitat Valenciana, Valencia, Spain.
²¹ Department of Microbiology and Ecology, University of Valencia Medical School, Valencia, Spain.
²² CIBERESP Network Center for Epidemiology and Public Health, Instituto de Salud Carlos III, Madrid, Spain.
²³ Vaccine Research Department, Fisabio-Public Health, Valencia, Spain.
²⁴ Universidad Católica de Valencia San Vicente Mártir, Valencia, Spain.
²⁵ Kenya Medical Research Institute (KEMRI), Nairobi, Kenya.
²⁶ Molecular Biology/Microbiology Research Laboratory, Universidade Federal Do Paraná, Curitiba, Brazil.

PMID: 40045898
PMCID: PMC11883289
DOI: 10.1111/irv.70085

Abstract

Background: This study aimed to establish a Severity Scale for influenza and other acute respiratory infections (ARI), requiring hospitalization, for surveillance and research purposes (the SevScale). Such a scale could aid the interpretation of data gathered from disparate settings. This could facilitate pooled analyses linking viral genetic sequencing data to clinical severity, bringing insights to inform influenza surveillance and the vaccine strain selection process.

Methods: We used a subset of data from the Global Influenza Hospital Surveillance Network database, including data from different geographical areas and income levels. To quantify the underlying concept of severity, an item response model was developed using 16 indicators of severity related to the hospital stay. Each patient in the dataset was assigned a Severity Score and a Severity Category (low, medium, or high severity). Finally, we compared the model scores across different subgroups.

Results: Data from 9 countries were included, covering between 4 and 11 seasons from 2012 to 2022, with a total of 96,190 ARI hospitalizations. Not for all severity indicators data were available for all included seasons. Subgroups with a high percentage of patients in the high Severity Category included influenza A(H1N1)pdm09, age ≥ 50, lower-middle income countries, and admission since the start of the COVID-19 pandemic.

Conclusions: The initial model successfully highlighted severity disparities across patient subgroups. Repeating this exercise with new, more complete data would allow recalibration and validation of the current model. The SevScale proved to be a promising method to define severity for influenza vaccine strain selection, surveillance, and research.

Keywords: acute respiratory infection; influenza; severity.

PubMed Disclaimer

Conflict of interest statement

Sandra S. Chaves is an employee of Sanofi, but the content of this paper is not representative of the views of their organization. Sandra S. Chaves contributed to the interpretation of results and the writing of the manuscript and report as a member of the Foundation for Influenza Epidemiology. Oana Săndulescu and Anca C. Drăgănescu report being investigators in the DRIVE project that has received support from the EU/EFPIA Innovative Medicines Initiative 2 Joint Undertaking (grant no. 777363) outside the scope of the submitted work and the GIHSN project, which was cofunded by the Foundation for Influenza Epidemiology, France, within the scope of the submitted work. Melissa K. Andrew and Sonia M. Raboni report grants from GSK, Sanofi, Pfizer, and Merck, unrelated to the present study. Marta C. Nunes reports grants from the Sanofi, unrelated to the present study, and personal fees from Pfizer and Sanofi, unrelated to the present study. F. Xavier Lopez‐Labrador reports grants and personal fees from Sanofi, unrelated to the present study. Shelly A. McNeil reports grants from Merck, Pfizer, and GSK unrelated to the present study and personal fees from Pfizer, Moderna, Merck, Sanofi, and GSK, unrelated to the present study. Bronke Boudewijns, Saverio Caini, Marco Del Riccio, Justin R. Ortiz, Joseph S. Bresee, Elena Burtseva, Daouda Coulibaly, Daria M. Danilenko, Kirill Stolyarov, Mine Durusu Tanriover, Heloisa I. G. Giamberardino, Parvaiz A. Koul, Ainara Mira‐Iglesias, Alejandro Orrico‐Sanchez, Nancy A. Otieno, Jorim Ayugi, and Peter Spreeuwenberg report no conflict of interest.

Figures

**FIGURE 1**
Age distribution of patients with acute respiratory infection per country.

**FIGURE 2**
Severity Score distribution. Displaying patients ranked from lowest to highest Severity Score (x‐axis), with their corresponding Severity Score.

See this image and copyright information in PMC

References

1. World Health Organization , “Factsheet Seasonal Influenza 2023,” [updated 12‐1‐2023, https://www.who.int/news‐room/fact‐sheets/detail/influenza‐(seasonal).
1. Iuliano A. D., Roguski K. M., Chang H. H., et al., “Estimates of Global Seasonal Influenza‐Associated Respiratory Mortality: A Modelling Study,” Lancet 391, no. 10127 (2018): 1285–1300. - PMC - PubMed
1. Paget J., Spreeuwenberg P., Charu V., et al., “Global Mortality Associated With Seasonal Influenza Epidemics: New Burden Estimates and Predictors From the GLaMOR Project,” Journal of Global Health 9, no. 2 (2019): 020421. - PMC - PubMed
1. Collaborators GBDI , “Mortality, Morbidity, and Hospitalisations Due to Influenza Lower Respiratory Tract Infections, 2017: An Analysis for the Global Burden of Disease Study 2017,” Lancet Respiratory Medicine 7, no. 1 (2019): 69–89. - PMC - PubMed
1. Ainslie K. E. C., Haber M., and Orenstein W. A., “Challenges in Estimating Influenza Vaccine Effectiveness,” Expert Review of Vaccines 18, no. 6 (2019): 615–628. - PMC - PubMed

Publication types

Actions

MeSH terms

Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions

Grants and funding

Foundation for Influenza Epidemiology

LinkOut - more resources

Full Text Sources
- PubMed Central
- Wiley
Medical
- MedlinePlus Health Information

Save citation to file

Email citation

Add to Collections

Add to My Bibliography

Your saved search

Create a file for external citation management software

Your RSS Feed

Severity Scale of Influenza and Acute Respiratory Illness Hospitalizations to Support Viral Genomic Surveillance: A Global Influenza Hospital Surveillance Network Pilot Study

Affiliations

Severity Scale of Influenza and Acute Respiratory Illness Hospitalizations to Support Viral Genomic Surveillance: A Global Influenza Hospital Surveillance Network Pilot Study

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

Publication types

MeSH terms

Grants and funding

LinkOut - more resources

Full Text Sources

Medical