Questions & Answers

Interim Report: Delayed Onset and Diminished Rotavirus Activity — United States, November 2007 – May 2008

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Questions and Answers

1. What is rotavirus?

Rotavirus is a virus that

• Causes severe diarrhea, mostly in infants and young children.
• Is often accompanied by vomiting, fever, and dehydration.
• Is the leading cause of diarrhea in infants and young children in the United States and worldwide.
• Infects almost all children in the United States before their 5th birthday.

2. Should we be concerned about rotavirus?

Each year in the United States, rotavirus is responsible for

• More than 400,000 doctor visits.
• More than 200,000 emergency department visits.
• Between 55,000 and 70,000 hospitalizations.
• Between 20 and 60 deaths among children less than 5 years of age.

Worldwide, rotavirus

• Accounts for about 527,000 deaths annually among children less than 5 years of age.
• Causes about 1,600 deaths each day among children less than 5 years of age.

3. How is rotavirus spread?

Rotavirus spreads easily.

• Large amounts of the virus are shed in the stool of infected persons and can easily be spread by contaminated hands and objects.
• Children can spread rotavirus both before and after they become sick with diarrhea, and they can pass the virus to household members and other close contacts.
• Among adults in the United States, rotavirus infection causes gastroenteritis (severe diarrhea, often with nausea, vomiting, and cramps) primarily among
  • Travelers returning from developing countries.
  • Parents and persons caring for children with rotavirus gastroenteritis.
  • Immunocompromised persons.
  • Older adults.

4. Is there a vaccine to protect against rotavirus?

Yes, RotaTeq® (pronounced “RO-tuh-tek”) vaccine can protect against rotavirus.

• The vaccine was licensed and recommended for use among infants in the United States in February 2006.
• The vaccine is produced by Merck & Co., Inc., Whitehouse Station, New Jersey.
• The vaccine is a liquid that is given by mouth rather than by injection.

5. How many doses of the rotavirus vaccine are recommended and at what age should they be given?

• Three oral doses of RotaTeq are recommended.
• Routine vaccination in the United States is recommended for infants at 2, 4, and 6 months of age.

6. How many infants and children in the United States have received a dose of the current rotavirus vaccine?

• National information on use of rotavirus vaccine is not yet available.
• A network of hospitals (sentinel sites) is closely following and reporting on rotavirus vaccine coverage and rotavirus disease. Information from this network shows that about 56% of infants aged 3 months had received one dose of rotavirus vaccine as of March 2008.
• About 34% of children aged 13 months at the sentinel sites had received all three doses as of March 2008.

7. When and in what pattern does rotavirus circulate in the United States?

• For many years, the U.S. rotavirus season has been observed to begin in November and end in May.
• The peak of the rotavirus season in the United States is usually in March.
• The season begins in the Southwest and then progresses quickly across the country to the Northeast

8. How has the current rotavirus vaccine impacted rotavirus circulation in the United States?

• The 2007–08 U.S. rotavirus season was delayed by about 3 months compared with the start time for the previous 15 years.
• The season began at the end of February instead of November, the usual start time.
• The season peaked at the end of April instead of March, the usual peak time.
• These delays were noted nationally and in each of the four U.S. census regions.
• In three study sites, the number of children being hospitalized or presenting to emergency departments with rotavirus during January 1–April 30, 2008 was approximately 90%–95% lower than during the same period in the previous 2 years.
• During January 1–May 3 (weeks 1–18), 2008, the number and percent of positive laboratory tests for rotavirus that were reported to CDC from a voluntary network of U.S. laboratories were lower than during the same weeks in the preceding 15 years.
• The number of laboratory tests performed for rotavirus was 37% lower than usual.
• The percent of all tests conducted for gastroenteritis that were positive for rotavirus was 79% lower than usual.

9. What are the implications of the delayed onset of the U.S. rotavirus season and of the lower level of peak activity?

• Activity in the ongoing 2007–08 rotavirus season appears substantially delayed in onset and diminished in magnitude compared with all previous available data.
  • Changes coincide with increasing uptake of the rotavirus vaccine among infants.
  • Changes appear to be greater than expected based on direct protective effects of vaccination alone, raising the possibility that this level of vaccination may be decreasing spread to unvaccinated individuals in the community (i.e., herd immunity).
• These unexpected findings require further study to confirm the impact of vaccination this year and further monitoring to determine the impact of the vaccine on rotavirus disease and its epidemiology over time.

10. How well does rotavirus vaccine work to prevent rotavirus disease?

Overall, about 72,000 healthy infants were studied worldwide in randomized placebo-controlled studies to look at both the safety of RotaTeq vaccine and how well it works.

• Data showing how well the vaccine prevents rotavirus gastroenteritis came from almost 7,000 infants from the U.S. and Finland. In U.S. participants, the vaccine
  • Prevented 74% of all rotavirus gastroenteritis cases.
  • Prevented 98% of the severe cases.
  • Reduced the need for hospitalization for gastroenteritis due to rotavirus by 96%.
  • A network of hospitals is closely following and reporting on rotavirus activity in the United States. The 2007–08 rotavirus season is ongoing; however, as of April 30, 2008, these hospitals reported that severe outcomes of rotavirus disease (hospitalizations, emergency department visits, physician visits) were 90%–95% lower than in previous 2 seasons

11. Is this the same rotavirus vaccine that was taken off the market because of problems?

No, this is not the same vaccine.

• In the 1999, a different rotavirus vaccine, RotaShield®, was removed from the market after it was found to be associated with a rare type of bowel obstruction called intussusception.
• The current vaccine, RotaTeq®, is different from the earlier vaccine; surveillance (close watching) for intussusception associated with the vaccine has found no evidence that RotaTeq causes intussusception.
• Before being licensed, RotaTeq’s safety was assessed in a large study involving more than 70,000 children.
• CDC and the Food and Drug Administration continue to very closely monitor RotaTeq vaccine to ensure there are no problems.

Additional Resources

• Additional information about rotavirus vaccine is available at http://www.cdc.gov/vaccines/vpd-vac/rotavirus/default.htm
• The Vaccine Information Statement (VIS), is available at http://www.cdc.gov/vaccines/pubs/vis/default.htm#rota
• Additional information about rotavirus disease is available at http://www.cdc.gov/rotavirus/about_rotavirus.htm
• Questions and answers about rotavirus vaccine are available visit http://www.cdc.gov/vaccines/vpd-vac/rotavirus/vac-faqs.htm

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