Erik Orberg, MD, PhD, University Hospital of the Technical University of Munich, Munich, Germany, highlights the importance of studying the intestinal fungal and viral communities in the allogeneic stem cell transplantation setting. Whilst bacteria are typically studied in the microbiome, fungal and viral populations are often overlooked. By identifying fungi via their ITS region and viruses via shotgun sequencing, researchers can investigate how different microorganisms interact with each other, especially when viral bacteriophages can alter bacterial functionality. This interview took place at the 63rd ASH Annual Meeting and Exposition congress in Atlanta, GA.