Does spatial proximity drive norovirus transmission during outbreaks in hospitals?

Harris, John P; Lopman, Ben A; Cooper, Ben S; O'Brien, Sarah J

The results show that the proximity metric (P) was larger than would be expected by chance under the null hypothesis (that proximity is not important) up to a serial interval of 2.5 days (p=0.05). outbreaks on hospital wards. We also performed sensitivity analysis using a serial interval distribution derived from a study of norovirus in children [13] . However, because the degree to which this generalizes to a hospital setting is unclear (intuitively the high contact rates in hospitals would be expected to lead to shorter serial intervals) [17] we explored serial intervals from 0.5 days to four days, whilst constraining the variance. Our results show that for serial intervals of less than 2 days the observed effect of proximity (sharing a bay with someone else who was ill) is very significant (p < 0.001) and for serial intervals up to 2.5 days remained significant at the 5% level. This pattern was similar whether using the observed serial interval distribution from the outbreak data or using a parametric probability distribution.