Responding to the Pandemic: Challenges With Public Health Surveillance Systems and Development of a COVID-19 National Surveillance Case Definition to Support Case-Based Morbidity Surveillance During the Early Response.

Responding to introductions of diseases and conditions of unknown etiology is a critical public health function. In late December 2019, investigation of a cluster of pneumonia cases of unknown origin in Wuhan, China, resulted in the identification of a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Multiple public health surveillance actions were rapidly implemented to detect introduction of the virus into the United States and track its spread including establishment of a national surveillance case definition and addition of the disease, coronavirus disease 2019, to the list of nationally notifiable conditions. Challenges in conducting effective case-based surveillance and the public health data supply chain and infrastructure are discussed.