Table 1 shows the clinical characteristics of the patients. We did not collect data on the healthcare workers involved other than treatment and outcomes. The timeline of the outbreak is shown in Figure 1. The presumed index patient (Patient no. 1) was a 6-year-old immunocompromised boy who presented to an outpatient clinic with respiratory symptoms. Influenza was suspected, a nasopharyngeal swab was obtained and the decision for hospitalization was made later that evening when at home, the patient's fever and symptoms worsened. The patient was hospitalized on the pediatric hematology-oncology unit, but was inadvertently not placed in isolation immediately. Isolation was instituted upon confirmation of the diagnosis a day later.