Pediatric cases represent a small part of COVID-19 cases reported worldwide and children seem to be mostly asymptomatic. The specific risks for patients in pediatric oncology wards are not well known yet. We describe here a pediatric hematopoietic stem cell transplant recipient infected by SARS-CoV-2. Despite being at high potential risk of a severe form of COVID-19 the patient we report only presented a rhinitis. She developed anti-SARS-CoV-2 IgM at D14 and IgG at D56 only and had a positive RT-PCR after 42 days. So far, it seems that in this fragile population COVID-19 is largely pauci-symptomatic.