Performance of the World Health Organization (WHO) severe acute respiratory infection (SARI) case definitions in hospitalized children and youth: cross-sectional study

Peter J Gill^{1

2

3

4}, Caitlyn L Kaziev², Haifa Mtaweh^{2

3

5}, Tuana Kant⁶, Claire Seaton^{7

8

9}, Daniel S Farrar^{2

10}, Hayley Wagman³, Mei Han¹¹, Rohini R Datta¹⁰, Sanjay Mahant^{1

2

3

4}, Gabrielle Freire^{2

3

12}, Aaron Campigotto^{13

14}, Jeffrey N Bone¹⁵, Manish Sadarangani^{9

16}, Francine Buchanan^{2

17}, Shaun K Morris^{2

3

10

18

19}; READAPT-Kids Study

Collaborators, Affiliations

Affiliations

¹ Division of Paediatric Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
² Child Health Evaluative Sciences, SickKids Research Institute, Toronto, Ontario, Canada.
³ Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada.
⁴ Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada.
⁵ Interdepartmental Division of Paediatric Critical Care Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
⁶ Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
⁷ Division of Pediatric Hospital Medicine, BC Children's Hospital, Vancouver, British Columbia, Canada.
⁸ BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
⁹ Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada.
¹⁰ Centre for Global Child Health, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹¹ Clinical Research Unit, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
¹² Division of Pediatric Emergency Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹³ Division of Microbiology, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹⁴ Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada.
¹⁵ Biostatistics Clinical Research Support Unit, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
¹⁶ Vaccine Evaluation Center, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
¹⁷ Centre for Innovation and Excellence in Child and Family-Centred Care, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹⁸ Division of Pediatric Infectious Diseases, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹⁹ Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.

PMID: 40083965
PMCID: PMC11904563
DOI: 10.1016/j.lana.2025.101034

Performance of the World Health Organization (WHO) severe acute respiratory infection (SARI) case definitions in hospitalized children and youth: cross-sectional study

Peter J Gill et al. Lancet Reg Health Am. 2025.

. 2025 Feb 21:44:101034.

doi: 10.1016/j.lana.2025.101034. eCollection 2025 Apr.

Authors

Affiliations

¹ Division of Paediatric Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
² Child Health Evaluative Sciences, SickKids Research Institute, Toronto, Ontario, Canada.
³ Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada.
⁴ Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada.
⁵ Interdepartmental Division of Paediatric Critical Care Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
⁶ Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
⁷ Division of Pediatric Hospital Medicine, BC Children's Hospital, Vancouver, British Columbia, Canada.
⁸ BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
⁹ Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada.
¹⁰ Centre for Global Child Health, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹¹ Clinical Research Unit, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
¹² Division of Pediatric Emergency Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹³ Division of Microbiology, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹⁴ Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada.
¹⁵ Biostatistics Clinical Research Support Unit, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
¹⁶ Vaccine Evaluation Center, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
¹⁷ Centre for Innovation and Excellence in Child and Family-Centred Care, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹⁸ Division of Pediatric Infectious Diseases, The Hospital for Sick Children, Toronto, Ontario, Canada.
¹⁹ Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.

PMID: 40083965
PMCID: PMC11904563
DOI: 10.1016/j.lana.2025.101034

Abstract

Background: Respiratory tract infections with viral pathogens are frequently identified using the World Health Organization (WHO) case definition of severe acute respiratory infection (SARI), defined as fever of ≥38°Celsius, cough, onset within 10 days, and hospitalization. While there is extensive research in adults, less is known about the WHO SARI case definition performance in children and youth. We aimed to determine the performance of the WHO SARI and modified case definitions in identifying viral respiratory tract infections in hospitalized children and youth.

Methods: Retrospective observational cross-sectional study of hospitalized children (0-18 years) with an acute respiratory infection and who received a respiratory viral test at two large Canadian children's hospitals from July 2022 to June 2023. The WHO SARI and modified SARI case definitions were evaluated overall, by virus and age, with reporting of sensitivity and specificity.

Findings: There were 2333 hospital admissions, with a median age of 2.4 years (IQR 0.8-5.0). 78% (n = 1828) had one or more viruses identified, most commonly respiratory syncytial virus (30%, n = 709). The WHO SARI definition had a sensitivity of 58% and specificity of 49% for identifying infections with a microbiologically confirmed virus. For Influenza only, the sensitivity was 71% and specificity 44%. The lowest sensitivity was among young children <3 months (28%) and 3 to <6 months (45%). Modified SARI definitions had similarly poor performance, with trade-offs of sensitivity and specificity.

Interpretation: The widely implemented WHO SARI case definition has sub-optimal performance among children and youth hospitalized with acute respiratory infections. Public health surveillance based on these case definitions may inadequately detect and monitor known and emerging infections, highlighting the need to develop an accurate and reliable SARI case definition for children and youth globally.

Funding: Public Health Agency of Canada, SickKids Foundation, BC Children's Hospital.

Keywords: Case definitions; Children; Diagnostic accuracy; Hospitalization; Paediatrics; Pandemics; Public health; Respiratory viruses; Sensitivity; Severe acute respiratory infections; Specificity; Surveillance; World Health Organization; Youth.

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Conflict of interest statement

Dr Gill has received grants from the Canadian Institute of Health Research (CIHR), the PSI Foundation, and The Hospital for Sick Children; he has received nonfinancial support from the CIHR Institute of Human Development, Child and Youth Health (as a member of the institute advisory board, expenses reimbursed to attend meetings); and he is a member of the Hospital Pediatrics and BMJ Evidence Based Medicine Editorial Board. Dr Mahant has received grants from the CIHR, the PSI Foundation, and The Hospital for Sick Children, and is a member of the Journal of Hospital Medicine Editorial Board. Dr Morris reports speaker fees from GlaxoSmithKline Canada and Sanofi-Pasteur, and has served on ad hoc advisory boards for GlaxoSmithKline Canada, Pfizer and Sanofi-Pasteur, all unrelated to this study. Dr Sadarangani is supported via salary awards from the BC Children’s Hospital Foundation and Michael Smith Health Research BC, and has been an investigator on projects funded by GlaxoSmithKline, Merck, Moderna, Pfizer and Sanofi-Pasteur; all funds have been paid to his institute, and he has not received any personal payments. Dr. Buchanan has received grants from the CIHR, support from the Academy of Medical Sciences (UK) to attend meeting, and honoraria from the American Academy for Cerebral Palsy and Developmental Medicine to attend conference. Dr. Seaton has received support from the Paediatric Inpatient Research Network to attend meeting. All other authors declare no conflict of interest.

Figures

**Fig. 1**
Diagnostic performance of the WHO SARI and modified SARI case definitions for any respiratory virus overall. This panel presents the sensitivity and specificity of each SARI definition for any respiratory virus from respiratory multiplex polymerase chain reaction (PCR) testing only. Definition 1 is the World Health Organization (WHO) Severe Acute Respiratory Infection (SARI) case definition. ∗Includes measured fever only, rather than reported or measured. SOB, shortness of breath. WOB, work of breathing. “Cough” (#3) is the same as the WHO “Extended SARI” case definition for hospital-based surveillance for severe RSV infection. However, some sites who use this definition include cough or shortness of breath, which would be the same as the definition of “cough OR SOB” (#5). These definitions are only meant for those >6 months of age, as the definition for those <6 months of age includes apnea and/or sepsis which is defined as: fever (>37.5 °C) or hypothermia (<35.5 °C); shock (lethargy, fast breathing, cold skin, prolonged capillary refill, fast weak pulse); and seriously ill with no apparent cause.

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References

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Performance of the World Health Organization (WHO) severe acute respiratory infection (SARI) case definitions in hospitalized children and youth: cross-sectional study

Collaborators

Affiliations

Performance of the World Health Organization (WHO) severe acute respiratory infection (SARI) case definitions in hospitalized children and youth: cross-sectional study

Authors

Collaborators

Affiliations

Abstract

Conflict of interest statement

Figures

References

LinkOut - more resources

Full Text Sources