The number of lives moderated risk-aversion in gain frame (people were risk-neutral for low number of lives and risk-averse for high number of lives). However, in the loss frame, risk-seeking was observed irrespective of how many lives were at stake. This pattern was consistent across laypersons and medical professionals, further extended to preferences for choices that medical professionals and artificial intelligence programmes should make. It shows how valuation of lives can be dependent on decision frames and framing biases that could impact medical decisions, which in turn could impact health and wellbeing of citizens.