Why experts call this COVID-19 wave a ‘silent’ threat

The U.S. faces a potential surge in COVID-19 cases—a wave, the 10th since the pandemic began, that experts say could take many by surprise due to its “silent” nature.

Unlike previous years, where winter waves began in November, this year’s surge has started later. Wastewater surveillance data from the Centers for Disease Control and Prevention (CDC) reveals a sharp increase in viral activity. As of December 21, SARS-CoV-2 levels are classified as “high” or “very high” in 28 states.

Michael Hoerger, a public health expert at Tulane University, describes this phenomenon as “silent transmission,” noting that many are unaware of the rising risk due to low activity levels earlier this fall. “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 only way of knowing whether we’re in a wave is if they’ve gotten sick,” he told TODAY.com.

Wastewater data and regional trends

The CDC has shifted its focus from tracking individual cases to monitoring wastewater, test positivity rates, and emergency department visits. Recent data shows:

• COVID-19 levels in wastewater have risen nationally, increasing from “low” in November to “high” by late December.
• States with “very high” activity include Arizona, Kentucky, and Massachusetts, among others.
• Test positivity rates stand at 7.5%, up nearly 2% from the previous week.

Symptoms and current variants

The dominant variants circulating, including XEC and KP.3.1.1, are highly transmissible but generally cause mild symptoms. Common symptoms include:

• Sore throat
• Congestion
• Fatigue
• Cough
• Fever or chills

Despite their mild nature, infections can still lead to severe outcomes, particularly for high-risk individuals, and contribute to the ongoing challenge of long COVID-19.

Vaccination and prevention

The CDC recommends the updated COVID-19 vaccine, which targets the KP.2 variant. This vaccine is expected to provide strong protection, though uptake remains low, with only 21% of U.S. adults vaccinated.

To mitigate the spread, health officials advise:

• Staying up to date on vaccinations.
• Testing for COVID-19 if symptomatic or exposed.
• Masking in crowded indoor settings.
• Staying home when unwell.