Costantini VP, Cooper EM, Hardaker HL, et al. - Given that human challenge studies, birth cohort studies, or vaccine trials in healthy adults have yielded most information on the mucosal and systemic immune response to norovirus infection, researchers here sought for data on immune responses to norovirus in the elderly. For this work, they prospectively enrolled 43 long-term care facilities in 2010-2014. They collected baseline saliva samples from 17 facilities and from cases and controls up to day 84 from 10 outbreaks as well as acute and convalescent sera. Baseline saliva samples of both symptomatic patients and asymptomatic shedders exhibited low norovirus-specific IgA levels and an increase in these levels was reported at day 5 after onset. The analysis revealed a strong correlation of salivary IgA levels with serum IgA titers and blockade antibodies; these levels remained elevated 3 months following a norovirus outbreak. In this study, a possible utility of a single salivary sample collected on day 14 was suggested for the identification of recent infection in a suspected outbreak or for monitoring population salivary IgA.