The Northeastern portion of the U.S. has been experiencing the biggest surge with over 13% of norovirus tests coming back positive for the bug since late January. The next highest region has been the Western part of the U.S., where test positivity rates have pushed above 12% in recent weeks. Now, these numbers are still lower than last Winter’s peaks that saw norovirus test positivity rates push well above 15% across the country.
Keep in mind that test positivity is only a very rough measure of overall norovirus activity. Such a measure depends on how many norovirus tests are ordered on a given day or during a given week. This, of course, can vary based on a a lot of different factors. For example, if there is more news of norovirus outbreaks, healthcare professionals may be more likely to order a norovirus test for someone with symptoms of some kind of gastroenteritis.