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. 2025 Oct 1;44(10):965-972.
doi: 10.1097/INF.0000000000004856. Epub 2025 May 15.

Severity of COVID-19 in Hospitalized Immunocompromised Children Across Canada

Costanza Di Chiara  1   2   3 , Tilmann Schober  4   5 , Daniel S Farrar  6 , Julie A Bettinger  7   8 , Olivier Drouin  3   9 , Joanne E Embree  10 , Scott A Halperin  11 , Charlotte Moore Hepburn  12 , Tajdin Jadavji  13 , Kescha Kazmi  1 , Rupeena Purewal  14 , Manish Sadarangani  7   8 , Laura Sauvé  1   7 , Karina A Top  12   15 , Fatima Kakkar  16 , Jesse Papenburg  4   17   18 , Shaun K Morris  1   3   19   20 ; for members of the Canadian Immunization Monitoring Program, ACTive (IMPACT)
Collaborators, Affiliations

Severity of COVID-19 in Hospitalized Immunocompromised Children Across Canada

Costanza Di Chiara et al. Pediatr Infect Dis J. .

Abstract

Background: The association of immunocompromised states with pediatric COVID-19 outcomes remains unclear. This study assessed COVID-19 severity in hospitalized children with and without immunocompromising conditions.

Methods: Children <17 years hospitalized in Canada for COVID-19 (April 2020-December 2022) were identified through the Canadian Paediatric Surveillance Program and Canadian Immunization Monitoring Program, ACTive. Immunocompromised children (IC) were those with immune-compromising conditions and/or on immunosuppressive treatment. Severe COVID-19 was defined as intensive care unit admission, ventilator/hemodynamic support, organ complications or death. Adjusted risk ratios (aRR) for severe COVID-19 among IC versus nonimmunocompromised children (non-IC) were calculated using Poisson regression, adjusting for age, sex, other underlying conditions, SARS-CoV-2 lineage and vaccination.

Results: Among 3218 children hospitalized for COVID-19, 354 (11.0%) were IC. IC were older [median age 6.7 years (interquartile range = 3.6-11.8)] than non-IC [1.2 years (interquartile range = 0.2-4.8); P < 0.001]. IC experienced less respiratory distress than non-IC (20.9% vs. 48.1%). Severe COVID-19 (14.1% vs. 29.0%; P < 0.001), respiratory support (16.1% vs. 35.6%; P < 0.001) and intensive care unit admission (5.9% vs. 17.4%; P < 0.001) were less frequent in IC. IC were less likely to have severe COVID-19 than non-IC [aRR = 0.46 (95% confidence interval [CI]: 0.32-0.65)], with both immunodeficiency [aRR = 0.53 (95% CI: 0.39-0.73)] and immunosuppression [aRR = 0.40 (95% CI: 0.23-0.73)] subcategories independently associated with reduced risk. Compared to non-IC with other conditions, IC had a lower risk of severe COVID-19 [aRR = 0.35 (95% CI: 0.25-0.47)].

Conclusions: Hospitalized IC exhibited a lower risk of severe COVID-19 than non-IC, potentially reflecting lower admission thresholds for IC with respiratory infections.

Keywords: COVID-19; children; immunocompromised; outcomes; severity.

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Conflict of interest statement

T.S. has received honoraria for lectures from Sanofi Pasteur, AstraZeneca and bioMérieux, all outside of the submitted work. O.D. and F.K. are supported by a Clinical Research Scholars Award from the Fonds de recherche du Québec – Santé. S.A.H. received funding from multiple vaccine manufacturers to undertake phase 1–3 clinical trials of candidate COVID-19 vaccines. F.K. received also honoraria for talks from ViiV and Equipment support for research from Altona Diagnostics, all outside of the submitted work. J.P. reported grants and personal fees from Merck and MedImmune, personal fees from AstraZeneca and Enanta and grants from MedImmune outside the submitted work. M.S. is supported via salary awards from the BC Children’s Hospital Foundation and Michael Smith Health Research BC. M.S. has also 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. J.B. reported funding from Public Health Agency of Canada and COVID Immunity Task Force directed to the Institution; she has not received any personal funds. S.A.H. reported grants from GSK, Pfizer, Moderna, Sanofi and others, outside the submitted work. S.A.H. also received consultant fees from Merck, Sanofi, GSK, Medicago, AstraZeneca and Seqirus. K.A.T. received grants from the Coalition for Epidemic Preparedness Innovations outside the submitted work. S.K.M. has received honoraria for lectures from GlaxoSmithKline, Pfizer and Sanofi Pasteur and has been a member of ad hoc advisory boards for Pfizer, Sanofi Pasteur and Apotex, all unrelated to this study. All other authors have no conflicts of interest to disclose.

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