Spatiotemporal trends in norovirus outbreaks in the United States, 2009-2019.

Timing and duration of the US norovirus season varied annually, but generally occurred during October-May. Norovirus wintertime seasonality was less distinct in western regions and was progressively more pronounced moving east. Further understanding the drivers of spatiotemporal dynamics of norovirus could provide insights into factors promoting virus transmission and help guide future interventions.