A 54‑year‑old man with a recent diagnosis of non‑Hodgkin’s lymphoma is currently undergoing R‑CHOP chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone). He attends the emergency department 7 days after his latest cycle, complaining of fever, rigours, and feeling generally unwell. On examination, he looks pale and unwell. His observations are: Temperature 38.6 °C. Heart rate 112 bpm, Blood pressure 95/60 mmHg, Respiratory rate 24/min, Oxygen saturation 95% on room air.