Rotavirus: The Childhood Infection a Vaccine Pushed to Every Other Year

Before a vaccine arrived in 2006, rotavirus was the leading cause of severe diarrhea among infants and young children in the United States, and almost every American child caught it before turning five. Each year it caused:

Since then the disease has dropped significantly — and even its calendar has changed. Outbreaks still happen, mostly where children go unvaccinated.

The virus

Under an electron microscope rotavirus looks like a wheel, which is where the name comes from: Latin rota, "wheel." It has no envelope, a triple-layered capsid and a segmented RNA genome, and it is stable in the environment — which is what lets it spread through more than direct contact.

Who gets sick, and how

Children are most at risk, especially those in childcare centers and other places full of young children. The most severe disease falls mainly on unvaccinated children aged 3 months to 3 years. Some adults are also at higher risk: older adults, people caring for children with rotavirus, and adults with weakened immune systems, such as people with HIV.

The virus spreads mainly by the fecal–oral route, usually person to person, but also through contaminated food or water and contaminated surfaces or objects. The incubation period is about 2 days. It can strike at any time of year; in temperate countries like the United States it is more common in winter and spring.

What it does

Vomiting and watery diarrhea for three to eight days, often with fever and abdominal pain, and sometimes loss of appetite and dehydration. Signs of dehydration:

• urinating less;
• dry mouth and throat;
• dizziness on standing;
• crying with few or no tears;
• unusual sleepiness or fussiness.

Neither vaccination nor infection gives complete immunity, so children can get rotavirus more than once. The first infection is usually the worst.

Diagnosis and treatment

Stool specimens are tested with PCR assays that detect rotavirus RNA — alone or in multipathogen panels — or with antigen-detection immunoassays. Strains can be characterized further by sequencing, though that is usually done only by surveillance and research laboratories.

There is no specific treatment. Care is mainly oral rehydration therapy to prevent dehydration; in people with healthy immune systems the illness resolves on its own in a few days.

What the vaccine changed

CDC recommends that infants receive either of the two available rotavirus vaccines, and advises clinicians to encourage parents to vaccinate.

• Before 2006, cases peaked every winter and spring in a wave that began in the Southwest in December and reached the Northeast by April and May.
• Since vaccination, rotavirus runs in a biennial pattern — every other year, with higher peaks in even years — and the seasons are shorter.

Fewer children receive rotavirus vaccine than other childhood vaccines, even though it is very effective against severe disease, and low vaccination rates lead to outbreaks; rotavirus is highly contagious.

CDC tracks the disease and the vaccine's impact through the National Respiratory and Enteric Virus Surveillance System (NREVSS) and the New Vaccine Surveillance Network (NVSN).

Sources

Based on "Clinical Overview of Rotavirus," Centers for Disease Control and Prevention; a work of the United States government in the public domain.