People with leukemia have a weakened immune system due to the disease itself and treatment, which leads to an increased susceptibility to infections. In a revised guideline, experts summarize the findings of the past ten years on all viruses that cause respiratory infections: How dangerous are they in detail? How are they diagnosed? Are hygiene measures necessary? What treatment and vaccination strategies are available? Professor Marie von Lilienfeld-Toal from the Institute for Diversity Medicine at Ruhr University Bochum, Germany, is the lead author of the recommendations of the European Conference on Infections in Leukaemia (ECIL) on the diagnosis, prevention, and treatment of community-acquired respiratory viral infections (CARV), which will be published on August 27, 2025 in the journal The Lancet Infectious Diseases.