The following protocol has been designed to investigate the First Few X cases (FFX) and their close contacts. It is envisioned that the FFX 2019-nCoV investigation will be conducted across several countries or sites with geographical and demographical diversity. Using a standardized protocol such as the protocol provided here, epidemiological exposure data and biological samples can be systematically collected and shared rapidly in a format that can be easily aggregated, tabulated and analyzed across many different settings globally for timely estimates of 2019-nCoV infection severity and transmissibility, as well as to inform public health responses and policy decisions. This is particularly important in the context of a novel respiratory pathogen, such as 2019-nCoV