Atlanta, Georgia — Flu activity across the United States has surged sharply, with 30 states now classified in the Centers for Disease Control and Prevention’s highest “very high” activity tier, as a fast-spreading influenza strain drives a nationwide spike in illness.
New data released Monday by the Centers for Disease Control and Prevention shows a dramatic acceleration in flu spread during the final week of December, coinciding with peak holiday travel and gatherings.
Flu cases jump sharply in just one week
Between December 20 and December 27, the CDC reported:
- A 33% increase in people testing positive for influenza
- An 8% rise in doctor visits for flu-like symptoms
The figures reflect delayed reporting due to the New Year holiday and include the critical Christmas week, when respiratory viruses historically spread more easily due to close indoor contact.
“Influenza activity continues to increase across the country,” the CDC said, warning that the U.S. may not have reached its seasonal peak yet.
From six states to 30 in highest-risk category
Earlier in December, before the holiday travel surge, only six states were classified as having “very high” flu activity.
As of December 27, that number has climbed to 30 states, spanning New England, the South, and much of the Midwest.
The states currently listed in the CDC’s “very high” flu activity category are:
Alabama, Alaska, Arkansas, Colorado, Connecticut, Florida, Georgia, Idaho, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Rhode Island, South Carolina, Tennessee, Texas, and Virginia.
Meanwhile, only four states — Montana, South Dakota, Vermont, and West Virginia — remain in the “low” to “moderate” range, according to the CDC.
‘Subclade K’ driving the surge
Health officials say the rapid rise is being fueled by a new influenza A variant known as “subclade K.”
This strain has already caused significant outbreaks in Canada, Japan, and the United Kingdom, where flu seasons tend to begin earlier than in the U.S.
In the U.K., the strain has placed heavy strain on hospitals.
“An unprecedented wave of super flu is putting immense pressure on the health care system,” said NHS National Medical Director Meghana Pandit.
U.S. experts say the international pattern raised early warning signs that America could see a similar surge once winter travel and gatherings intensified.
Vaccination concerns raise alarms
Public health experts are increasingly worried that lower-than-normal flu vaccination rates could worsen the impact of the current season.
While vaccines remain effective at reducing severe illness, hospitalizations, and deaths, uptake has lagged in several age groups compared to previous years.
“It is not too late to get a flu shot,” said Dr. Andrew Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health, during a December media briefing.
“We’re really at the beginning of the influenza season here in the U.S.”
Peak flu season may still be weeks away
Historically, flu activity in the U.S. often peaks in February, even though cases usually begin climbing in December.
That timeline has health officials concerned that January and February could bring even higher case counts, particularly if vaccination rates do not improve.
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Experts caution that the current surge may represent the buildup to the peak, not the peak itself.
Hospitals in several high-activity states have already reported increased emergency room visits and rising inpatient admissions tied to flu complications.
Who is most at risk right now
Doctors say certain groups remain especially vulnerable as flu activity accelerates:
- Older adults
- Young children
- People with weakened immune systems
- Those with chronic heart, lung, or metabolic conditions
Health officials urge anyone experiencing high fever, shortness of breath, chest pain, confusion, or dehydration to seek medical care promptly.
What people can still do
Despite the rapid spread, experts stress there are still ways to reduce risk:
- Get vaccinated, even now
- Avoid close contact when sick
- Wash hands frequently
- Wear masks in crowded indoor settings, especially in high-risk states
“We still have time to blunt the worst outcomes,” health experts say, noting that vaccination and early treatment can significantly reduce severe cases.
As flu activity continues to rise across much of the country, health officials say the next few weeks will be critical in determining how severe the 2026 flu season ultimately becomes.
Is flu activity noticeably worse where you live this winter? Are people around you getting sick more often than usual? Share what you’re seeing in the comments below.
