CBS A new strain of norovirus now makes up a majority of outbreaks nationwide, according to data from the Centers for Disease Control and Prevention. The new strain’s emergence, found spreading throughout the country and on cruise ships, offers a possible explanation for the past month’s steep wave of infections from the stomach bug.
Scientists call this winter’s dominant norovirus strain GII.17[P17]. Samples from patients in nearly 7 in 10 norovirus outbreaks have tested positive for the new strain so far this season, according to data from a network of public health laboratories called CaliciNet.
“It is too early to tell if this strain is associated with more severe norovirus disease but likely lower population immunity is the reason for the early surge of an otherwise seasonal increase of this virus,” Jan Vinjé, head of the CDC’s CaliciNet system, told CBS News in an email.