Clinical Characteristics and Disease Severity Among Infants With SARS-CoV-2 Infection in Montreal, Quebec, Canada

With more than 40 million cases of confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection worldwide, the clinical presentation and risk factors for disease severity among adults and children have now been well described.¹ SARS-CoV-2 is the virus that causes coronavirus disease 2019. However, little remains known about disease manifestation and severity of illness in infants.² Although infants are at higher risk of severe disease and complications from other common viral respiratory pathogens (influenza, respiratory syncytial virus), it is not yet clear whether this is the case with SARS-CoV-2 infection because few series describing outcomes in infants have been published.^3,4 The objective of this study was to describe the manifestations and severity of disease among infants with SARS-CoV-2 infection.

This case series describes all infants younger than 1 year with laboratory-confirmed SARS-CoV-2 infection (confirmed a by positive reverse transcriptase–polymerase chain reaction result) who were diagnosed or treated at Centre Hospitalier Universitaire Sainte-Justine (CHU-SJ), Montreal, Quebec, Canada, between February 14 and May 31, 2020. The study was approved by the CHU-SJ research ethics board with the requirement for informed consent waived owing to the retrospective nature of the study. Clinical features and severity of disease were compared between infants younger than 3 months chronologic age (younger infants) and infants 3 to 12 months old (older infants). Disease severity was defined using the widely used criteria from Dong et al.⁵ The Appropriate Use and Reporting of Uncontrolled Case Series in the Medical Literature guideline (https://www.ajo.com/article/S0002-9394(10)00690-2/fulltext) was the reporting guideline for this case series. Variables were compared using the Wilcoxon rank sum or Fisher exact test where appropriate, using a 2-sided α level, with P < .05 considered statistically significant. Statistical analyses were performed with Stata, version 12.1 software (StataCorp).

Of 1165 infants who were tested for SARS-CoV-2 infection at CHU-SJ during this 2020 study period, 25 (2%) had confirmed positive results, and 8 of those with positive results (32%) required hospitalization. Two additional infants with SARS-CoV-2 positive results were transferred directly to CHU-SJ for hospitalization and are included in the analysis. Of those 27 infants, 15 (56%) were male, the median age was 89 days (interquartile range [IQR], 34-193 days), and 7 (26%) had comorbid conditions.

Table 1 describes clinical manifestations and disease severity among all infants. Disease was mild in most cases (24 infants [89%]) of cases. The most common presenting symptoms were gastrointestinal tract symptoms (23 infants [85%]), followed by fever (temperature ≥38.0 °C (22 [81%]), and upper respiratory tract symptoms (16 [59%]). There were no significant differences in clinical manifestation between older vs younger infants. However, there was a higher incidence of comorbid conditions among older vs younger infants (6 older infants [46%] vs 1 younger infant [7%]; P = .03), including lower birth weight (median [IQR] birth weight, 2055 g [988-2886 g] among older infants vs 3138 g [2998-3505 g] among younger infants; P = .02) and gestational age (median [IQR] age at birth, 34.0 wk [30.0-37.0 wk] among older infants vs 38.8 wk [38.5-39.6 wk] among younger infants; P = .05). Five infants (19%) had concurrent urinary tract infections caused by Escherichia coli.

Clinical characteristics and laboratory and imaging findings of the 10 hospitalized infants are described in Table 2. Three of the hospitalizations (30%) were determined to be non-SARS-CoV-2–related (urinary tract infection, n = 2; intussusception, n = 1). Disease was again mild in most (7 [70%]) of hospitalized patients; none of the infants required supplemental oxygen. The single admission to the intensive care unit was for a non-SARS-CoV-2–related infection (urosepsis from E coli).

In this case series report, we describe the first series, to our knowledge, of infants with SARS-CoV-2 infection reported from Canada. Our findings are consistent with previous series describing infants who present with mainly fever, mild disease, and no need for mechanical ventilation or intensive care treatment.^3,4 However, the proportion of hospitalization among the 25 infants tested at our center (32%) was lower than that reported by the US Centers for Disease Control and Prevention (62%) among 95 infants with known hospitalization status.⁶ We suspect this higher risk may reflect practice in the early phase of the pandemic, when in the absence of data, infants may have been hospitalized out of an abundance of caution. These results suggest that no additional SARS-CoV-2–related investigations may be necessary for the majority of infants.

Our study is limited by its small sample size, retrospective observational study design, and testing indications that followed public health guidelines. As a result, we have included only symptomatic infants in our analysis and potentially overestimate the severity of illness.

Clinical signs and disease severity among infants in our series differ from those reported in children and older adults. Our patients had a predominance of gastrointestinal tract symptoms, even in the absence of fever, and mild disease overall. Given these differences, further work should be done to understand the pathophysiological mechanisms underlying the immune response to infection in infants, as this may be a key to addressing the underlying the morbidity associated with SARS-CoV-2 infection in adults.

Accepted for Publication: October 21, 2020.

Published: December 14, 2020. doi:10.1001/jamanetworkopen.2020.30470

Correction: This article was corrected on February 5, 2021, to fix the spelling of the third author’s first name in the byline.

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Panetta L et al. JAMA Network Open.

Corresponding Author: Fatima Kakkar, MD, MPH, Division of Infectious Disease, Department of Pediatrics, Centre Hospitalier Universitaire Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montreal, QC H3T 1C5, Canada (fatima.kakkar@umontreal.ca).

Author Contributions: Drs Kakkar and Panetta had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Panetta, Proulx, Autmizguine, Luu, Kakkar.

Acquisition, analysis, or interpretation of data: Panetta, Proulx, Drouin, Autmizguine, Quach, Kakkar.

Drafting of the manuscript: Panetta, Kakkar.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Kakkar.

Obtained funding: Kakkar.

Administrative, technical, or material support: Panetta, Luu, Quach.

Supervision: Drouin, Kakkar.

Conflict of Interest Disclosures: None reported.

Funding/Support: This work was supported by a Réseau SIDA Maladies Infectieuses coronavirus disease 2019 COVID-19 grant to Dr Kakkar that provided funding for the design and conduct of the study, data collection and, management. Drs Kakkar, Drouin, Luu, Autmizgine, and Quach are supported by Fonds de Recherche Santé clinician investigator grants that provide salary support for protected time that allowed for data analysis and manuscript preparation.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and the decision to submit the manuscript for publication.

Additional Contributions: The authors thank all members of the CHU-Sainte Justine COVID-19 response team, including the COVID-19 outpatient clinic team leader (Geneviève Parisien, BSc), infection control prevention team (Nadia Demarais, RN, and Gaelle Anick Delisle, MSc), pediatric infectious diseases team (Bruce Tapiero, MD, Valerie Lamarre, MD, Philippe Ovetchkine, MD, Marc Lebel, MD, Chantal Buteau MD, and Ana Blanchard, MD, MSc), medical microbiology team (Christian Renaud MD, MSc, Emilie Valières MD, PhD, and Julie Blackburn, MD), and research team of the Centre d’Infectiologie Mère-enfant (Silvie Valois RN, and Suzanne Taillefer, PhD) for their work in rapidly establishing the clinical and research infrastructures needed to address the COVID-19 pandemic at CHU-Sainte-Justine.