Mild COVID-19 clinical course among paediatric patients with primary immunodeficiency

BACKGROUND: The clinical course of coronavirus disease-2019 (COVID-19) varies from those who are asymptomatic, experience mild symptoms such as fever, cough, and dyspnea, to more severe outcomes including acute respiratory distress, pneumonia, renal failure, and death. Early reports suggested severe outcomes in patients with primary immunodeficiency (PID), particularly those with type 1 interferon signalling defects. This prompted a rigid approach to social distancing to protect this patient population, particularly children. To date, real-world data describing the course and outcome of COVID-19 in paediatric PID patients remains scarce. METHODS: In this retrospective case series, we describe the clinical course of 36 paediatric patients with underlying primary immunodeficiency (PID) followed by SickKids Hospital (Toronto, Canada) who were symptomatic and tested positive for SARS-CoV-2 infection between October 2020 to November 2022. RESULTS: Our cohort consisted of patients with combined immunodeficiency (66.7%), antibody deficiency (22.2%), neutrophil dysfunction (8.3%), and immune dysregulation (2.8%). The median age was 7.5 years (range: 8 months – 17 years), with 21 male and 15 female patients. Three (8.3%) patients were post-hematopoietic stem cell transplant (HSCT) and 12 (33%) patients were on immunoglobulin replacement. Nine (25%) patients had underlying lung problems including bronchiectasis (1), interstitial lung disease on home oxygen therapy (1), and underlying asthma (7). Most patients had mild clinical course and were managed at home. The most common symptoms were fever (80%), cough (75%) and other upper respiratory tract symptoms (72%). Nineteen (52.7%) patients experienced other symptoms which included headache, lethargy, or gastrointestinal upset. At the time of the infection, 13 patients (36.1%) had received 2 doses of a SARS-CoV-2 vaccine, 5 patients (13.9%) had received 1 dose, and 18 (50%) were not vaccinated. None of the patients received antiviral or monoclonal antibody as prophylaxis or treatment. Only 1 patient required hospital admission out of precaution given the close proximity to HSCT. All patients recovered without complications. CONCLUSION: The paediatric patients with PID followed by our centre experienced mild to moderate COVID-19 symptoms and recovered fully without complications. These findings support the return of much needed social interactions among children, which were impacted severely during the COVID-19 pandemic.