The COVID-19 pandemic has led a number of countries to introduce restrictive ‘lockdown’ policies on their citizens in order to control infection spread. Immunity passports have been proposed as a way of easing the harms of such policies, and could be used in conjunction with other strategies for infection control. These passports would permit those who test positive for COVID-19 antibodies to return to some of their normal behaviours, such as travelling more freely and returning to work. The introduction of immunity passports raises a number of practical and ethical challenges. In this paper, we seek to review the challenges relating to various practical considerations, fairness issues, the risk to social cooperation and the impact on people’s civil liberties. We make tentative recommendations for the ethical introduction of immunity passports.