This year's winter COVID wave is off to a later start than usual, and health experts are warning about a potential "silent" surge in transmission over the holiday season.
They're calling it "silent" because this winter wave follows a long period of unusually low COVID activity this fall, so many people are unaware that COVID levels have risen sharply over the past two weeks.
Wastewater data from the Centers for Disease Control and Prevention shows a sharp uptick in COVID levels in the past two weeks, with 21 states reporting "high" or "very high" viral activity. Those states include: Arizona, Arkansas, District of Columbia, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Massachusetts, Minnesota, Missouri, Nebraska, New Hampshire, New Mexico, Ohio, Pennsylvania, Rhode Island, South Carolina, South Dakota and Wyoming.
Experts warn that people may not be aware of the increasing risk of infection, leading to potential spread at holiday gatherings and during travel.
"There's a good chance that a lot of people are going to get sick in the next couple of weeks and be unaware of it," Dr. Michael Hoerger, director of the Pandemic Mitigation Collective, told TODAY.com. Most people are not tracking CDC data, and so their only way of knowing whether we're in a wave is if they've gotten sick."
While the U.S. is not yet in a large COVID surge, uncertainty remains about the severity and duration of this winter wave, which came "out of nowhere," Hoerger said.
"The issue with this winter's wave is it's a lot different than previous ones," Hoerger told TODAY. "Normally people would have had a month or so of warning by now, seeing friends and family getting infected. Transmission was freakishly low for November, and so people are kind of lulled into a false sense of security."
"This is a very risky time in terms of lots of people interacting indoors, so we don't really know how quickly transmission can pick up," he added.
The best way to stay virus smart is by following the three Vs, according to Dr. Peter Chin-Hong, UCSF Professor of Psychology and Family Medicine.
"The first is, of course, getting up to date on vaccines. I think some of the groups that people might forget about, kids in particular, we haven't thought about kids as much as older adults for COVID," Dr. Chin-Hong told KCBS Radio. "The second, of course, is ventilation. And the third very easy thing to do is to keep your hands very clean."