With the new year just beginning, the respiratory virus season is kicking in strong.
The latest surveillance data from the Centers for Disease Control and Prevention (CDC) show that the level of acute respiratory illness causing people to seek healthcare is “high” and continuing to increase nationally.
Emergency room visits for flu and RSV (respiratory syncytial virus) are considered “very high” and climbing, while COVID-19 emergency department admissions are low but also on the rise.
For the week ending December 28, more than 26,000 people were admitted to hospitals with influenza. That number represents about 7.8 per 100,000 hospitalized people compared with 2.4 per 100,000 for RSV.
“Most of the current surge is being driven by high influenza activity as well as RSV,” says Peter Chin-Hong, MD, an infectious disease specialist and a professor of medicine at the University of California San Francisco School of Medicine. “RSV came first in November, followed by influenza in December. RSV is possibly at its peak now and being overtaken by influenza as the respiratory virus driving emergency department visits and hospitalizations nationally.”
Test Positivity and Wastewater Indicators Are Climbing
Another sign of viral activity is test positivity (the percentage of tests that come back positive for a disease), and flu is now the leader, with the positivity rate at the end of December jumping to nearly 19 percent from 13 percent the previous week.
Compared with the week prior, RSV rose to 12.8 percent from 10.7 percent, and weekly COVID test positivity inched up just 0.1 percent to 7.1 percent.
Wastewater (sewage) testing, however, suggests that COVID cases may soon shoot up. Because traces of infectious disease circulating in a community can be detected in wastewater, testing can provide an early warning if infections are on the upswing. Currently, the level of COVID activity in wastewater is at “high,” while measures for flu and RSV are both “moderate.”
“You're likely to see upticks [of viral activity] in wastewater measurements sometimes several weeks before you actually observe an increase in clinical cases,” says Dean Winslow, MD, an infectious-disease specialist and a professor of medicine at Stanford University in California. “COVID-19 hit a low point in November, but as wastewater shows it may pick up again.”
It’s the Most Virus-Filled Time of the Year
While respiratory illnesses are expected to keep growing throughout the country, 10 states in particular are currently experiencing “very high” levels of infections: Arizona, Florida, Georgia, Kansas, Kentucky, New Hampshire, Oklahoma, Tennessee, Texas, and Utah.
“I don’t see a common thread as to why these states in particular are seeing the highest levels of activity,” says Erica Prochaska, MD, a pediatric infectious diseases specialist with Johns Hopkins Children’s Center in Baltimore. “Unfortunately, I suspect that the states that have lower numbers now are probably going to have higher numbers over the next few weeks because that’s typically what happens.”
Public health authorities note that widespread sickness this time of year is not unusual, as many people have been traveling and gathering inside for the holidays. Spending more time indoors during the colder weather tends to fuel viral activity.
“In addition, low humidity this time of year may make viral particles lighter and more easily spread,” says Dr. Chin-Hong.
It Can Be Challenging to Know if You Have Flu, RSV, or COVID-19
Because symptoms of flu, RSV, and COVID-19 are similar, it can be difficult to distinguish between illnesses caused by these respiratory viruses, according to the National Foundation for Infectious Diseases (NFID).
Common symptoms include cough, headaches, sneezing, runny nose, and congestion. NFID says that aches, fatigue, and fever occur often with flu; difficult breathing, fatigue, and sore throat occur often with COVID-19; and wheezing is a frequent and distinguishing symptom with RSV.
To definitely diagnose a case, a healthcare professional may use a test, and that may help determine treatment, such as with antiviral drugs specifically for flu or COVID-19 — although with basic care such as rest and hydration, most of these illnesses get better on their own.
Preventing Spread Can Protect the Most Vulnerable
Generally, people at higher risk of getting severely ill from respiratory viruses are older adults, young children, people with compromised immune systems, people with disabilities, and pregnant people.
In looking at flu-related hospitalizations in the last three months of 2024, for example, the highest cumulative hospitalization rate per 100,000 population was among adults ages 65 years and older (38.6), followed by adults ages 50 to 64 years (15.1), and children ages 0 to 4 years (12.2).
When it comes to RSV, the CDC says emergency department visits and hospitalizations have been highest in children and hospitalizations are elevated among older adults in some areas.
To help reduce severe illnesses, the American Lung Association recommends adopting these habits to prevent transmission:
Cover your cough or sneeze, preferably with a tissue.
Keep your distance from people who are sick.
Stay home when sick.
Clean and disinfect surfaces when someone is sick at home.
Consider wearing a mask to protect against circulating viruses.
Wash hands regularly.
“Frequent hand-washing is probably one of the best protections,” says Dr. Winslow, who warns that we all have to touch doorknobs, railings, and the like, which can be contaminated with viruses.
It’s Not Too Late to Get Vaccinated
Chin-Hong adds that vaccination is the most effective way to prevent severe illness from respiratory viruses, and the public should make sure they are up to date with recommended vaccines for flu, COVID-19, and RSV.
“There is still time to get vaccinated,” he says. “Influenza in particular has a long tail of infection that can extend into April. COVID is famously unpredictable so it may still emerge later in the season — I would vaccinate now if unvaccinated this year, especially for those who are older than 65 and/or immunocompromised.”
Tom Gavin joined Everyday Health as copy chief in 2022 after a lengthy stint as a freelance copy editor. He has a bachelor's degree in psychology from College of the Holy Cross.
Prior to working for Everyday Health, he wrote, edited, copyedited, and fact-checked for books, magazines, and digital content covering a range of topics, including women's health, lifestyle, recipes, restaurant reviews, travel, and more. His clients have included Frommer's, Time-Life, and Google, among others.
He lives in Brooklyn, New York, where he likes to spend his time making music, fixing too-old electronics, and having fun with his family and the dog who has taken up residence in their home.
Don Rauf has been a freelance health writer for over 12 years and his writing has been featured in HealthDay, CBS News, WebMD, U.S. News & World Report, Mental Floss, United Press International (UPI), Health, and MedicineNet. He was previously a reporter for DailyRx.com where he covered stories related to cardiology, diabetes, lung cancer, prostate cancer, erectile dysfunction, menopause, and allergies. He has interviewed doctors and pharmaceutical representatives in the U.S. and abroad.
He is a prolific writer and has written more than 50 books, including Lost America: Vanished Civilizations, Abandoned Towns, and Roadside Attractions. Rauf lives in Seattle, Washington.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
