As the incidence of COVID-19 cases increases, it will at some point no longer be feasible, or efficient, to trace all contacts of confirmed cases, thus discontinuing active case finding. This will probably happen at different points in time in different countries. We characterise this as progression to Scenario 3a: Widespread sustained transmission with increasing pressure on the healthcare system. The objective would then shift from containment to mitigation, requiring substantial risk communication effort to ensure that the public knows how to respond in case of a suspected infection. Countries may consider the implementation of social distancing measures such as cancellation of conferences, cultural or sport events or the recommendation of teleworking or school closures in order to slow transmission of the virus. Such measures may reduce the acute burden on healthcare systems and possibly delay and/or reduce the peak of an outbreak. In this phase, it may be essential to simplify case reporting and test for SARS-CoV-2 in specimens from syndromic primary healthcare and hospital-based influenza surveillance systems. Detections of SARS-CoV-2 via influenza surveillance would initially be an indicator of transmission in the community and over time would allow the spread, intensity and severity of the virus to be described. Preparations should be made for efficient triage of cases requiring medical attention and for cohort isolation of cases requiring treatment. Citizens should be advised on what they can do to reduce pressure on the healthcare system.