Rotavirus Outbreaks After the Vaccine: Three California Outbreaks, 2017

This page describes three outbreaks in 2017 and the vaccine coverage figures current when they were reported.

Before rotavirus vaccine was introduced in 2006, rotavirus was the most common cause of severe diarrhea among U.S. children. Two licensed vaccines have since proven 78%–89% effective in real-world use against moderate to severe rotavirus illness, and they have cut rotavirus disease substantially. But coverage lags: the most recent national estimates at the time showed 73% of children completing the rotavirus series, compared with 95% receiving at least 3 doses of vaccines against diphtheria, tetanus and pertussis, given on a similar schedule. Rotavirus still circulates in a pattern that peaks every other year.

A report by CDC and California's state and local health departments describes three outbreaks in 2017. One person died, but most illness was mild to moderate, and cases occurred at all ages and in vaccinated children.

Outbreak 1: a child care center in Long Beach

In late March 2017, the Long Beach Department of Health and Human Services learned of acute gastroenteritis at a child care center serving 80 children aged 2 to 5, 135 more in after-school care, and 27 staff. The department stressed handwashing, gave cleaning advice matching that for norovirus, and told parents to keep sick children home until 48 hours after symptoms ended; the center later closed for a deeper clean.

• Cases: 27 children and 4 staff by April 17, plus 5 household contacts. The 2-year-old and 3-year-old classrooms were hit hardest (attack rates of 43% and 37%).
• Symptoms (31 patients): diarrhea 71%, vomiting 55%, abdominal cramps 42%, fever 38%, nausea 13%. Ages ranged from 2 to 86, median 4. Three saw a doctor; no one was hospitalized.
• Testing: norovirus was suspected, but four stool samples tested negative for it. The California Department of Public Health's Viral and Rickettsial Disease Laboratory found rotavirus in all of them, and CDC typed it as G12P[8].
• Vaccination: the state registry showed 6 of the 27 sick children (22%) had been vaccinated, 4 of them fully. Coverage may have been higher, because providers are not required to use the registry and the center did not require proof of vaccination.

Outbreak 2: an assisted living and memory care home in San Mateo

In early April 2017, San Mateo County health officials were notified of an outbreak at an assisted living and memory care facility with 44 residents and 40 staff. They recommended the standard measures: isolating and grouping the sick, contact precautions, suspending group activities, handwashing, and disinfecting with bleach or an EPA-approved product effective against norovirus.

By April 10, 9 people were ill, 4 residents and 5 staff. All had diarrhea, two had cramps and one vomited. They were aged 22 to 90 (median 47), and none had been eligible for rotavirus vaccine. At least one saw a doctor; no one was hospitalized. Again norovirus was suspected, and again the samples were negative for it but positive for rotavirus, genotype G12P[8].

Outbreak 3: a subacute care facility for children in Santa Clara County

On May 1, 2017, the Santa Clara County Public Health Department learned of an outbreak at a subacute inpatient facility for patients under 21 with complex medical needs. The facility stepped up bleach cleaning, isolated and grouped patients, canceled group activities and stopped admissions, and a site visit found good hand hygiene and contact precautions. Even so, 24 of the facility's 25 patients and 3 of its 115 staff fell ill between April 24 and May 17.

Symptoms lasted a median of 7.5 days; 85% had diarrhea and 56% vomiting. Patients ranged from 6 months to 39 years old (median 2). Most recovered without major complications, but a 22-month-old child with preexisting respiratory failure died of dehydration caused by rotavirus. That child and 16 other patients had never received rotavirus vaccine, and three more had received only one dose. A hospital multipathogen PCR panel found rotavirus in 11 of 14 samples and no other pathogen; four of five samples typed by CDC were G12P[8], and the fifth was G12.

What the outbreaks show

Rotavirus still appears sporadically year-round and in winter–spring epidemics every other year, even among the vaccinated, and it affects adults as well as young children, especially those living in group settings.

• Vaccinated children can still get sick. The vaccines are highly effective against severe diarrhea, but do not necessarily prevent infection or milder illness, so outbreaks can happen even where coverage is high.
• Adults get rotavirus too. Adults are not vaccinated, though vaccinating children may protect them indirectly. As multipathogen PCR testing spreads, more adult outbreaks may be recognized. Rotavirus outbreaks are often first taken for norovirus, and the age of those affected should not rule rotavirus out.
• The most vulnerable children were the least protected. The Santa Clara outbreak, with the highest attack rate and a death, struck a fragile population with low vaccination coverage. Most of its patients had spent time in neonatal or pediatric intensive care, where live virus vaccines are discouraged, and many were too old to start rotavirus vaccine by the time they left; the series must begin by 14 weeks 6 days of age and be completed by 8 months. The authors suggest more research on the risks and benefits of that practice.

The same G12P[8] strain appeared in all three outbreaks, probably because it had been the most common strain in the United States in recent years. Both vaccines work against it, but lagging coverage leaves many children open to severe disease.

Control and prevention

Control measures for rotavirus are much the same as for norovirus: hand hygiene, isolating and grouping the sick, and disinfecting surfaces. Clean with soap and water, then apply a 1,000–5,000 ppm chlorine solution for 5 minutes, which is 5–25 tablespoons (2.5–12.5 ounces) of household bleach (5.25% sodium hypochlorite) per gallon of water, or use an EPA-registered disinfectant effective against norovirus. Clinicians and public health workers should consider rotavirus in gastroenteritis at any age, and keep promoting vaccination of eligible infants according to CDC recommendations.

Sources

• Burke RM, Tate JE, Barin N, et al. "Three Rotavirus Outbreaks in the Postvaccine Era — California, 2017." MMWR 67(16). https://www.cdc.gov/mmwr/volumes/67/wr/mm6716a3.htm