In the wake of winter waves of COVID, flu, and RSV – the so-called “triple-demic” – another virus has reared its ugly head. It seems norovirus, also called the "winter vomiting bug”, might be back with a vengeance: while outbreak data isn’t up to date, data on positive tests suggests cases in the US may have already surpassed last year's peak.
According to the Centers for Disease Control and Prevention (CDC) surveillance data, the percentage of positive tests nationwide was 17 percent as of February 11, and appears to still be rising. Last year, test positivity was around 15.5 percent at the outbreaks’ peak in March.
Regional data, however, suggests the number of norovirus cases may now be petering off in the Northeast, Midwest, and Western US. Though they still appear to be rising in the South.
After a brief break for COVID, infectious diseases have had a renaissance, and norovirus is no exception. Outbreaks were at an eight-year low in the latter half of 2020 and the beginning of 2021, the CDC's Norovirus Sentinel Testing and Tracking (NoroSTAT) data indicate. But by the end of last February, they’d spiked, exceeding the number of outbreaks since surveillance began in 2012.
The outbreak data for 2022-2023 hasn’t been updated since early January, but at this point, the number of outbreaks was higher than it was in both of the previous seasons. Worryingly, outbreaks also seem to be on a steep incline, but of course, this could have changed in the weeks since.
Norovirus is known for causing gastroenteritis, with symptoms including vomiting and diarrhea. In the US, outbreaks occur most frequently during late fall, winter, and early spring, so we’re not out of the woods yet and may be seeing norovirus around for a good few months to come.
[H/T: Ars Technica]