What is the optimal skill mix for virtual wards? Do new roles such as clinical pharmacists or advanced practitioners act as substitutes for, or additions to, existing staff? What works to retain staff? How much do current rates of attrition and turnover cost the NHS and social care? Evidence gaps in workforce research are holding back healthcare improvements, say Tara Lamont, Cat Chatfield, and Kieran Walshe in this BMJ opinion piece.