Rotavirus vaccine cuts severe child illness as norovirus outbreaks rise

Rotavirus can turn dangerous fast, especially for babies and toddlers. Ben Lopman, a professor of epidemiology, global health and environmental health at Emory University’s Rollins School of Public Health, saw it happen in his own family when his 18-month-old son went from energetic to totally listless in just 48 hours.

The Centers for Disease Control and Prevention says rotavirus is the leading cause of vomiting and diarrhea in infants and young children in the United States, and it can cause severe watery diarrhea, dehydration, hospitalization and death. Symptoms commonly last three to eight days and can include vomiting, watery diarrhea, fever, abdominal pain, loss of appetite and dehydration, a combination that can weaken a small child quickly.

Before vaccine introduction, rotavirus was the leading cause of severe diarrhea among U.S. infants and young children. Each year it drove more than 400,000 doctor visits, more than 200,000 emergency room visits, 55,000 to 70,000 hospitalizations and 20 to 60 deaths among children younger than 5. The vaccine has changed that picture sharply. CDC estimates the rotavirus vaccine prevents 40,000 to 50,000 hospitalizations among U.S. infants and young children every year.

Two oral rotavirus vaccines are licensed in the United States. The first dose is due before a child is 15 weeks old, and the series must be completed by 8 months of age. That timing matters because the disease can escalate rapidly once symptoms begin, and the smallest children are least able to withstand dehydration.

The broader gastrointestinal picture is worsening on the norovirus side. NoroSTAT-participating states reported 907 norovirus outbreaks from August 1, 2025 through March 5, 2026, according to CDC surveillance. That is below the 2,115 outbreaks reported during the same period a year earlier, but CDC still describes the network as near-real-time monitoring for outbreak activity and circulating strains, a sign that transmission remains active across the country.

Taken together, the numbers show a split screen for child stomach illnesses: one vaccine has pushed down the worst rotavirus outcomes, but norovirus is still moving through communities, and the risk for the youngest children remains concentrated in the same early, vulnerable months of life.