Norovirus Regional Trends

Participating U.S. laboratories report the total number of norovirus tests performed that week, and the number of those tests that were positive to CDC weekly. Because reporting delays may be expected for some laboratories, data shown for the more recent weeks may be less complete than others. Each point on the trend graphs below displays the average percent of tests that were positive from three adjacent weeks: the specified week, and the weeks preceding and following it. This is also known as a centered 3-week moving average.

In the United States, outbreaks of norovirus occur most frequently during late fall, winter, and early spring. There may be variation in the timing of outbreaks between regions and between communities in the same region.

Census Region Image Map, Census Region Selector

Northern: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont Midwestern: Illinois, Indiana, Iowa, Michigan, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin Western: Alaska, Arizona, California, Colorado, Hawaii, Idaho, Nevada, New Mexico, Montana, Oregon, Utah, Washington and Wyoming Southern: Alabama, Arkansas, Delaware, District of Columbia, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia and West Virginia Florida

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Southern United States Census Region

SVG: Southern United States percent positive Rotavirus tests, by week

Table: Southern United States percent positive norovirus tests, by week


Northeastern United States Census Region

SVG: Northeastern United States percent positive Rotavirus tests, by week

Table: Northeastern United States percent positive norovirus tests, by week


Midwestern United States Census Region

SVG: Midwestern United States percent positive Rotavirus tests, by week

Table: Midwestern United States percent positive norovirus tests, by week


Western United States Census Region

SVG: Western United States percent positive Rotavirus tests, by week

Table: Western United States percent positive norovirus tests, by week