Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread internationally. COVID-19 is placing unprecedented pressure on the global healthcare workforce and many healthcare workers have been infected. In Italy, for example, almost 1 in 10 infections have occurred in healthcare workers. Preventing infections in healthcare workers has been identified as a key strategic objective by the WHO and is vital for health services that are likely to be faced with unprecedented demand. Hydroxychloroquine is active against SARS-CoV-2 in vitro. It has an established role in malaria prophylaxis with weekly dosing and costs 8 cents per tablet. We plan a randomised clinical trial that will evaluate the role of hydroxychloroquine for SARS-CoV-2 prophylaxis in front-line healthcare workers. The primary end point will be laboratory confirmed SARS-CoV-2. The trial will start if the number of cases of COVID-19 increases in New Zealand from the current levels, and will involve a range of frontline healthcare workers.