Quantifying the roles of vomiting, diarrhea, and residents vs. staff in norovirus transmission in U.S. nursing home outbreaks

Carly Adams; David Young; Paul A Gastañaduy; Prabasaj Paul; Zach Marsh; Aron J Hall; Benjamin A Lopman

Outbreak data 110 De-identified data from six separate and unique nursing home outbreaks from two 111 consecutive norovirus seasons (2014-2015 and 2015-2016) were provided by the South Carolina 112 Department of Health and Environmental Control (SCDHEC). All outbreaks were confirmed, 113 meaning they had at least two laboratory confirmed norovirus cases. Outbreak data were in the 114 form of line lists and included individual-level information on symptom onset dates, reported 115 symptoms (vomiting, diarrhea, and fever), age in years, sex, illness duration, hospitalization, 116 emergency department visit, and whether the case was a resident or staff. Probable cases were 117 defined as residents or staff who had at least one episode of vomiting and/or three or more loose 118 stools within a 24-hour period. Confirmed cases were probable cases with a laboratory confirmed 119 norovirus infection. As this was an analysis of anonymized data that had already been collected 120 through routine public health response, the Emory University Institutional Review Board (IRB) 121 determined that this study was exempt from IRB review. Transmissibility of a pathogen can be quantified by its basic reproduction number, R 0 , 125 defined as the average number of secondary cases generated by a single infectious individual in a This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available for use under a CC0 license.