ABSTRACT
Contact tracing is the process of identifying, assessing, and managing people who have been exposed to a disease to prevent onward transmission. It is an essential public health tool and a crucial component to the on-going COVID-19 pandemic response in Lagos State, Nigeria. This contact tracing exercise is the largest one to be conducted in the megacity and is leveraging on the expertise of professionals across different strata of the health care system. Following the confirmation of a positive case of COVID-19; the State's contact tracing team commenced investigations by identifying contacts and following them up daily for 14 days from the last point of exposure. In the process of conducting this large-scale exercise, several lessons that can improve contact tracing outcomes such as the need for community mobilizers and decentralization, the importance of technology and communication campaigns were learnt and can serve as good practice for other implementers.