Rotavirus Season Milder and Shorter

(June 27, 2008) - A new vaccine for rotavirus (Read about "Rotavirus") seems to be taking hold. The annual rotavirus season this year was shorter and milder, according to the Centers for Disease Control and Prevention (CDC). Rotavirus activity in the ongoing 2007-2008 season appears to have started later than usual and has been less severe than during any of the previous seasons.

Rotavirus is the leading cause of severe gastroenteritis (vomiting and diarrhea) in infants and young children. (Read about "Gastroenteritis") It annually causes about 410,000 physician office visits, 205,000-272,000 emergency department visits (Read about "Emergency Room"), 55,000-70,000 hospitalizations, and between 20 and 60 deaths among US children less than 5 years of age. Worldwide, rotavirus causes approximately 1,600 deaths each day among children less than 5 years of age.

Data from around the United States indicate that during the ongoing season, rotavirus activity was delayed by about three 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, and the season peaked at the end of April instead of March, the usual peak time.

CDC says the report indicates that the changes in rotavirus activity may be due to a newly introduced rotavirus vaccine for infants. In 2006, a new rotavirus vaccine, RotaTeq, was recommended for routine immunization of U.S. infants at 2, 4 and 6 months of age. (Read about "Immunizations") Clinical trial results indicated that this live, oral vaccine prevented 74 percent of all rotavirus cases, about 98 percent of severe cases, and about 96 percent of hospitalizations due to rotavirus. "The changes appear to be greater than expected based on the protective effects of the vaccine alone," said Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases at CDC. "It is also possible that current levels of vaccination may be helping to decrease the spread of rotavirus to unvaccinated individuals in the community."