This year’s winter COVID wave is off to a later start than usual, and some experts are warning about a potential “silent” surge in transmission over the holidays.
They’re calling it “silent” because there was less COVID activity than usual this past fall, so many people are unaware that rates have sharply risen over the past two weeks, the most recent data on COVID activity in wastewater from the U.S. Centers for Disease Control and Prevention show.
As a result, people may not know their risk of infection is increasing and not test if they have only mild symptoms, which can cause the virus to spread at holiday gatherings, during travel and more.
“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. Most people are not tracking CDC data, and so their way of knowing whether we’re in a wave is if they’ve gotten sick,” Michael Hoerger, Ph.D., associate professor at Tulane University School of Medicine and public health expert on tracking COVID-19 trends, tells TODAY.com.
While the current data does not yet show the U.S. is in a COVID surge, the country is entering its 10th COVID wave since the pandemic started, Hoerger adds.
But there’s a great deal of uncertainty about how bad this wave will be and how long it will last. “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,” Hoerger says.
A risk of “silent” transmission over the holidays
While the U.S. is not currently seeing a large COVID surge, there has been a clear uptick in the last two weeks, according to data from the CDC. And cases are likely to continue to increase.
“As of Friday, December 20, COVID-19 levels in wastewater are moderate nationally,” Dr. Jonathan Yoder, deputy director of the CDC Division of Infectious Disease Readiness and Innovation, tells TODAY.com. Wastewater data from the prior week was “low” nationally. Levels are highest in the Midwest.
“Nationally, COVID-19 levels in wastewater have been increasing through the month of December, following a period of low levels in October and November,” Yoder adds.
The CDC no longer tracks the total number of new COVID cases in the U.S., instead estimating transmission levels using wastewater surveillance, test positivity and emergency department visits.
COVID test positivity is at 5.6%, up 0.5% from the previous week, per CDC data. COVID-related emergency room visits and deaths are also increasing very slightly.
“The issue with this winter’s wave is it’s a lot different than previous ones,” Hoerger explains. “Transmission was freakishly low for November, and so people are kind of lulled into a false sense of security.”
COVID-19 levels are ticking up about a month later than usual, Hoerger adds, which puts the country into “uncharted territory.”
“You can think of the start of the wave as kind of a silent transmission period where people aren’t really aware of it, and that’s coinciding with the start of holiday travel,” says Hoerger.
Hoerger, who is the director of the Pandemic Mitigation Collective, which uses the COVID-19 forecasting model, projects that as of Dec. 16, one in 64 (1.6%) people are actively infectious in the U.S., and there are about 750,000 new daily infections, and these are rising.
This COVID-19 wave is coming on late and “out of nowhere,” he wrote on X.
Other experts agree that infections are expected to go up in the coming weeks.
“We anticipate that these holiday gatherings and traveling and all that will provide opportunities for an increase in COVID, as well as (influenza) and RSV,” Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, tells TODAY.com.
“It’s silent (transmission) because most of these infections are quite mild so people are not testing, or they’re blowing them off as a cold.”
While the late summer COVID surge may mean that the U.S. population still has some immunity, it’s likely starting to wane, the experts say. And the current variants circulating, including XEC and the decedents of the FLiRT family, are highly transmissible and cause a lot of milder infections that go largely undetected.
“The communicability of these viruses is contributing to a silent epidemic, if you will,” says Schaffner.
Where COVID is spreading in the US
Wastewater levels are currently “high” or “very high” in 21 states, according to the latest data from the CDC. According to the CDC’s wastewater viral activity levels, as of Dec. 14, are:
- 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
- Wyoming
“If you see increased COVID-19 wastewater viral activity levels in your area, it might indicate that there is a higher risk of infection,” says Yoder.
However, regional variation in wastewater data can also depend on the number and specific location of wastewater surveillance sites that are monitoring, says Hoerger. Some states have no data, and others only have limited coverage. “Take regional variation with a grain of salt,” says Hoerger.
COVID-19 symptoms in 2024
The symptoms caused by the dominant variants circulating, XEC and KP.3.1.1, are very similar to those caused by previous omicron subvariants, according to experts. Common COVID-19 symptoms include:
- Sore throat
- Congestion
- Runny nose
- Cough
- Fatigue
- Headache and body aches
- Fever or chills
- Shortness of breath
- Nausea or loss of appetite
- Diarrhea
- Loss of sense of taste or smell
Symptoms will vary from person to person. Even milder infections can be “debilitating” for several days, says Schaffner.
Although the latest COVID-19 variants appear to be causing milder infections, it can still cause severe illness requiring hospitalization. Certain people are at higher risk of developing severe disease. These include people over the age of 65, people with underlying medical conditions, and people who are immunocompromised.
Every time a person is infected with COVID, they are at risk of developing long COVID, which can cause symptoms that persist and reemerge for weeks or months after infection, per the CDC.
Are new COVID boosters effective?
The updated COVID-19 vaccine for 2024–2025 is recommended by the CDC for everyone ages 6 months and older.
The new mRNA COVID vaccine is monovalent, which means it targets one variant — in this case, the KP.2 “FLiRT” variant. The strains currently circulating are closely related to KP.2, and the new booster should provide good protection, TODAY.com previously reported.
“The best protection is to get vaccinated. Although vaccinated people sometimes get infected with the virus that causes COVID-19, staying up to date on COVID-19 vaccines significantly lowers the risk of getting very sick, being hospitalized, or dying from COVID-19,” says Yoder.
How to protect yourself against COVID-19
When COVID-19 levels are rising, it’s important for people to take steps to protect themselves and their families, according to the CDC.
You can take the following actions to prevent COVID-19:
- Stay up to date on COVID-19 vaccinations.
- Test if you have symptoms or an exposure.
- Stay home when sick.
- Seek treatment for COVID-19 if you are at high risk.
- Wear a mask.
- Practice social distancing.
