Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly identified pathogen and it is assumed there is no pre-existing human immunity to the virus. Initial seroconversion, including neutralizing antibodies, has been documented and there is some evidence that immunity to SARS-CoV-2 re-challenge during early convalescence is likely. Continue reading “Case Definition for Coronavirus Disease 2019 (COVID-19)”