Topline
Recent data from the Centers for Disease Control shows spikes in norovirus, Covid-19 and RSV across the U.S.—a resurgence that’s potentially unlike the usual annual winter spread of these illnesses, which have been less active in recent months.
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Key Facts
Norovirus is a contagious virus that typically presents as projectile vomiting and diarrhea after ingesting contaminated food or drink, interacting with contaminated surfaces or interacting with a sick individual, and it is the most common foodborne virus.
Reported norovirus cases spiked in late November and grew by nearly 31% percent increase to 91 reported outbreaks nationally in the first week of December—the highest level of the year and a near three-year high; from 2021 to 2024, the largest number of reported outbreaks at the start of December was 41 cases, although just 14 states report norovirus outbreaks to the CDC.
Respiratory syncytial virus (RSV) is a common virus that manifests with similar symptoms to the flu but can be especially deadly for babies and older individuals; it’s currently identified as moderately active from wastewater testing but is increasingly the cause of emergency room visits nationally, more so than the flu or Covid-19, the CDC reports.
The CDC estimated there were more than 29,000 hospitalizations from RSV and more than 1,300 deaths since Oct. 1 nationally; it estimated RSV caused more hospitalizations in December than the previous month, with wastewater showing elevated numbers in Kentucky, Georgia, Louisiana, Connecticut and Massachusetts.
Covid-19 currently has lower levels of emergency visits than other respiratory viruses, but it has been found readily in wastewater, with the CDC rating its activity level higher than the flu or RSV after it started to multiply in December, partly because of a new contagious variant spreading, called XEC.
That’s an unexpected change from the recent Covid-19 respite of October and November, particularly in the Midwest, where there are nearly two times more infections than in the rest of the U.S., and it’s a change from the past pattern of Covid-19’s spread bottoming out around the end of December.
How Can I Avoid Getting Sick?
Those who spend more time in crowded, indoor environments are generally more likely to be infected, and it’s common to catch these illnesses on cruise ships or in classrooms. Respiratory viruses often spread through the air. Norovirus can spread through touching infected objects. Those traveling for the holidays or spending time with family should wash their hands more regularly and avoid contact with sick individuals. The CDC also recommends vaccines in advance to reduce the severity of illnesses and respiratory viruses.
What Do Experts Say About Covid-19 Surging?
Michael Hoerger, a Tulane University School of Medicine researcher, described the infection boom in an X post as a “silent surge” that “came out of nowhere” in December after depressed levels with the highest percent increase in three years. This latest wave, the 10th wave so far, has not reached the same infection levels of previous waves. Hoerger added, citing his predictive modeling based on CDC data, that there’s a 23% chance of catching the virus at a party of 10 people. That’s partly because of a new variant of the virus spreading rapidly, called XEC, potentially making it easier for people to get sick.
What Is The New Covid-19 Variant Xec?
XEC has become the dominant strain of Covid-19 spreading in the U.S., according to Yale Medicine. The variant originated from Germany and appeared first in June of 2024. It is a recombinant strain, or a combination of two past subvariants. Past vaccinations will likely protect against XEC, according to Yale Medicine.
Key Background
These illnesses are reported yearly when they spread in winter and fall months and are some of the most common viruses. Other common winter illnesses include the flu and whooping cough. More than 2,500 cases of norovirus are reported each year, and more than 2 million outpatient doctor visits are made annually because of RSV. However, spiking infections mean a heightened risk of infection. RSV has become more prevalent in recent years, especially among older adults and young children. Donald DeCoy, a pulmonologist at the Cleveland Clinic, said in an interview that a decrease in Covid-19 precautions after the pandemic might be one reason for this, as well as the fact the U.S. population of older adults is larger than ever. The Washington Post reported the near-record spike in norovirus could be because the pandemic kept more individuals indoors, causing fewer infections and less overall immunity.
Who Is Most Likely To Get Sick?
These illnesses most affect older adults, those with underlying illnesses or weak immune systems, and young children.
Are These Viruses Deadly?
RSV can lead to lung infections that can be deadly and potentially worsen pre-existing illnesses like asthma or heart failure. Norovirus symptoms can lead to dehydration, which can be fatal. Covid-19 treatment has improved and lowered the risk of death, but it can still cause serious symptoms that can linger and cause infections. However, it still accounts for 1.1% of all deaths in the U.S. as of December 21, 2024. Older adults and those with other illnesses are also more at risk of becoming more severely sick or dying from Covid-19.
How Long Do Symptoms Usually Last?
Individuals usually get sick within about four to six days if infected with RSV, and symptoms can last longer than a week. Covid-19 symptoms can show up after two days or two weeks of infection and can last for more than a month in extreme infections. Norovirus is generally quicker, with symptoms starting about a day after infection, and some may feel better after two days.
What Should You Do If You Think You’re Infected?
No treatment exists for norovirus, and sick people are advised to hydrate and eat simple foods after symptoms start to abate. For those suffering from RSV-like symptoms, rest and hydration are generally the only treatment advisable, but medical attention is urged for those having trouble breathing. For Covid-19 symptoms, tests and medications are available to lessen the side effects, but they must be taken soon after the infection.
