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

In the final multivariable model, cases who vomited infected 2.74 (95% CI: 1.90, 3.94) 270 more individuals than non-vomiters, cases with diarrhea infected 1.62 (95% CI: 1.09, 2.41) more 271 individuals than cases without diarrhea, and resident-cases infected 1.69 (95% CI: 1.18, 2.42) 272 more individuals than staff-cases (Fig 3) . In sensitivity analyses where cases with R Ei = 0 were 273 included in the regression analysis, stronger associations between infectiousness and vomiting, 274 diarrhea, and resident/staff status were observed (2.96, 1.90, and 1.89, respectively). Adding a 275 dichotomous variable (index vs. non-index case) to the model indicated that index cases infected 276 6.64 (95% CI: 3.49, 12.63) more individuals than non-index cases, holding resident vs. staff, 277 diarrhea, and vomiting constant. Furthermore, we examined the associations between outbreak 278 day, counting the first illness onset date as day one, and case characteristics and found cases who 279 vomited occurred 2.7 (95% CI: 1.8, 3.6) days earlier in the outbreak than cases who did not 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.