Every policy has direct and indirect effects of intended and unintended consequences. Policies that require people to stay at home to reduce the morbidity and mortality from Covid-19 will have effects beyond the virus. For example, they will adversely affect mental health and economic prospects for many. They will also affect people’s willingness and ability to access health and social services. This is likely to result in increases in morbidity and mortality from otherwise curable diseases, such as cancer, acute myocardial infarction and stroke. A comparison between Covid-19 deaths prevented and excess cancer deaths caused shows it is possible that preventing Covid-19 deaths through lockdowns might result in more life-years being lost than saved.