Respiratory illness activity in South Carolina is currently low overall, according to CDC surveillance data. That said, several infections are still circulating across the state, including COVID-19, norovirus, and a notable rise in vaccine-preventable diseases like whooping cough in the Upstate region.
Respiratory Viruses: COVID-19, Flu, and RSV
The CDC classifies South Carolina’s overall acute respiratory illness level as “low.” COVID-19 wastewater monitoring, one of the most reliable ways to track how much virus is actually circulating, also shows low viral activity in the state. The COVID-19 reproduction rate sits at about 1.09, meaning each infected person is spreading it to roughly one other person. That’s enough to keep cases trickling along but not enough to fuel a surge.
Flu and RSV activity has also wound down from winter peaks. If you’re feeling run down with a cough, sore throat, or congestion, a respiratory virus is still a possibility, but community spread is relatively quiet compared to the height of winter.
Norovirus Is Hitting the Southeast Hard
The bigger story this season has been norovirus, the highly contagious stomach bug that causes sudden vomiting, diarrhea, and stomach cramps. Nationally, cases more than doubled the previous peak this winter, and the Southeast has been no exception. MUSC Health’s Charleston campus alone recorded 80 positive norovirus tests over a recent three-month stretch. Health officials attribute the spread to close contact in households, schools, and community settings.
Norovirus spreads incredibly easily. A tiny amount of the virus, picked up from contaminated surfaces, food, or close contact with a sick person, is enough to cause infection. Symptoms typically hit hard and fast, lasting one to three days. The main risk is dehydration, especially in young children and older adults. Frequent handwashing with soap and water (not just hand sanitizer, which doesn’t kill norovirus well) is the most effective prevention.
Whooping Cough and Measles in the Upstate
South Carolina’s Department of Public Health has flagged a concerning trend in the Upstate region: a measurable increase in vaccine-preventable diseases over the past several years. Between 2020 and 2025, the Upstate experienced 23 outbreaks of vaccine-preventable illnesses. Seven of those were whooping cough outbreaks, totaling 470 cases. Measles and chicken pox cases have also appeared.
Whooping cough starts with what feels like a mild cold, then progresses into intense coughing fits that can last for weeks. It’s especially dangerous for infants who are too young to be fully vaccinated. The state health department is urging Upstate residents in particular to check that their vaccinations are current, but the message applies statewide. If you’re hearing a persistent, severe cough going around your community, pertussis is worth considering.
RSV Hospitalizations Are Down for Babies
One piece of good news for parents: RSV hospitalizations among infants have dropped significantly compared to pre-pandemic years, largely thanks to newer preventive treatments. Nationally, hospitalization rates for babies under eight months fell by about 43% during the 2024-25 season compared to the 2018-20 baseline. The biggest drop was among the youngest infants, under three months old, where hospitalizations fell by roughly half. These reductions coincide with the introduction of preventive immunization products for newborns and pregnant mothers.
RSV still circulates every winter and remains a leading cause of hospitalization in very young children, but the trend is moving in the right direction.
Spring Allergies Are Already Here
Not everything that feels like sickness is an infection. South Carolina’s tree pollen season is already underway, with pollen counts running high in areas like Charleston. If your symptoms are mainly sneezing, itchy or watery eyes, and a clear runny nose without fever or body aches, allergies are a likely culprit. Ragweed, mold, and grass pollen remain low for now, but tree pollen alone is enough to make many people miserable through early spring.
The easiest way to tell the difference: allergies don’t cause fever, and they tend to produce itchiness (eyes, nose, throat) rather than the body aches and fatigue that come with infections. If your symptoms get worse outdoors or on windy days, pollen is probably the driver.