Clinical manifestations and disease severity of SARS-CoV-2 infection among infants in Canada
Authors: Piché-Renaud Pierre-Philippe , Panetta Luc , Farrar Daniel S. , Moore-Hepburn Charlotte , Drouin Olivier , Papenburg Jesse , Salvadori Marina I. , Laffin Melanie , Kakkar Fatima , Morris Shaun K. ,   the Canadian Paediatric Surveillance Program COVID-19 Study Team
Published: February 2022

AbstractImportanceThere are limited data on outcomes of SARS-CoV-2 infection among infants (<1 year of age). In the absence of approved vaccines for infants, understanding characteristics associated with hospitalization and severe disease from COVID-19 in this age group will help inform clinical management and public health interventions.ObjectiveThe objective of this study was to describe the clinical manifestations, disease severity, and characteristics associated with hospitalization among infants infected with the initial strains of SARS-CoV-2.DesignProspective study of infants with SARS-CoV-2 from April 8th 2020 to May 31st 2021.SettingNational study using the infrastructure of the Canadian Paediatric Surveillance Program, reporting inpatients and outpatients seen in clinics and emergency departments.ParticipantsInfants <1 year of age with microbiologically confirmed SARS-CoV-2 infection.ExposureInfant-level characteristics associated with hospitalization for COVID-19.Main outcomes and MeasuresCases were classified as either: 1) Non-hospitalized patient with SARS-CoV-2 infection; 2) COVID-19-related hospitalization; or 3) non-COVID-19-related hospitalization (e.g., incidentally detected SARS-CoV-2). Case severity was defined as asymptomatic, outpatient care, mild (inpatient care), moderate or severe disease. Multivariable logistic regression was performed to identify characteristics associated with hospitalization.ResultsA total of 531 cases were reported, including 332 (62.5%) non-hospitalized and 199 (37.5%) hospitalized infants. Among hospitalized infants, 141 of 199 infants (70.9%) were admitted because of COVID-19-related illness, and 58 (29.1%) were admitted for reasons other than acute COVID-19. Amongst all cases with SARS-CoV-2 infection, the most common presenting symptoms included fever (66.5%), coryza (47.1%), cough (37.3%) and decreased oral intake (25.0%). In our main analysis, infants with a comorbid condition had higher odds of hospitalization compared to infants with no comorbid conditions (aOR=4.53, 2.06-9.97), and infants <1 month had higher odds of hospitalization then infants aged 1-3 months (aOR=3.78, 1.97-7.26). In total, 20 infants (3.8%) met criteria for severe disease.Conclusions and RelevanceWe describe one of the largest cohorts of infants with SARS-CoV-2 infection. Overall, severe COVID-19 in this age group is uncommon with most infants having mild disease. Comorbid conditions and younger age were associated with COVID-19-related hospitalization amongst infants.Key PointsQuestionWhat are the spectrum of illness, disease severity, and characteristics associated with hospitalization in infants with SARS-CoV-2 infection?FindingsA total of 531 cases were reported to the Canadian Paediatric Surveillance Program, including 332 (62.5%) non-hospitalized and 199 (37.5%) hospitalized infants. In total, 20 infants met criteria for severe disease (3.8%). Infants’ characteristics associated with admission included age of less than one month and comorbid conditions.MeaningThis study provides data on the spectrum of disease, severity, and characteristics associated with admission due to COVID-19 in infants, which informs clinical management and public health interventions in this specific population.