The 16th ACH2 annual scientific workshop was held at Peppers Cragieburn, Bowral, NSW from 2-4th June 2021, organised by Joanne Camilleri, Chaturaka Rodrigo, Nadia Warner, Andrew Harman and Jennifer Juno. Guest speakers were Sharon Lewin (HIV), Xionan Zhang (Hepatitis), Rowena Bull (Hepatitis), Kirstie Bertram (HIV), Wen Shi Lee (COVID-19) and Damian Purcell (HTLV).