Oct. 27, 2008 (Washington, D.C.) -- A vaccine against rotavirus, an infectious disease that causes potentially deadly diarrhea in infants, has led to a remarkable drop in hospitalizations and visits to the emergency room, researchers say.
There's even evidence the vaccine reduced spread of the infectious disease to children who were not immunized, the researchers say.
The findings were presented at a joint meeting of the American Society for Microbiology and the Infectious Diseases Society of America.
"The success of the rotavirus vaccine is a major theme of this meeting," says meeting co-chairman Michael Scheld, MD, of the University of Virginia School of Medicine in Charlottesville.
Rotavirus' Grim Toll
Prior to introduction of the vaccine, rotavirus took a grim toll in both industrialized and developing nations, researchers say. Among some of the statistics cited:
- No. 1 cause of diarrhea-related hospitalizations and deaths in babies and young children
- Responsible for about 400,000 physician visits, more than 200,000 emergency room visits, up to 70,000 hospital admissions, and 60 deaths every year in the U.S. alone
- Causes 2 million hospitalizations worldwide annually
- Blamed for nearly half a million deaths annually in children under 5 years.
Since the vaccine's introduction, though, things have taken a 100% turn for the better, says Christopher Mast, PhD, of Merck Research Laboratories, maker of the vaccine.
A company-funded study of more than 61,000 infants showed that RotaTeq provided complete protection against hospitalizations and emergency room visits because of strains of rotavirus targeted by the vaccine.
"RotaTeq provided 100% protection against hospital and emergency department visits due to rotavirus when administered during routine public health practice," Mast tells WebMD.
The study involved 33,135 infants who were vaccinated and 27,954 who were not.
Costs also fell, he says. Since the vaccine's introduction, expenditures dropped from $12,000 per infant per year in the unvaccinated group to nothing in the vaccinated group.
RotaTeq, which gained FDA approval in February 2006, is an oral vaccine given at 2, 4, and 6 months of age. In June, a second rotavirus vaccine came on the market -- GlaxoSmithKline's Rotarix. It requires only two doses, completed by 4 months of age.
Unlike an earlier rotavirus vaccine that was pulled from the market, the two new vaccines do not appear to raise the risk of intussusception. An emergency condition in which the intestine folds into itself like a telescope, intussusception can cause intestinal blockage from swelling and inflammation.
Other research presented at the meeting confirmed RotaTeq's success story:
- A study by researchers at Quest Diagnostics Inc., of Madison, N.J., showed that 26% of 27,625 rotavirus tests done at company labs around the country were positive for rotavirus in the three years before the vaccine was licensed. In the most recent peak season, which ran from December 2007 to June 2008, only 8% of 21,873 tests were positive.
"In the three years before the vaccine became available, more than one out of every four tests submitted was positive for rotavirus. This season fewer than one in 12 were," says Quest's Jay Lieberman, MD.
Of note was that the rate of positive tests fell in every age group, including those aged 2 to 6 years, he says.
"Because children older than 2 years are unlikely to have been vaccinated, these data suggest a herd immunity phenomenon. [This] occurs when enough children get vaccinated so that transmission of the virus is interrupted in the community and even unvaccinated children are unlikely to get disease," Lieberman tells WebMD.
- A CDC study showed that the number of confirmed cases of rotavirus plummeted more than 80% in the 2007-2008 season, compared with the previous two years.
- At the University of Massachusetts Medical School in Worcester, there was a "dramatic decrease" in rotavirus cases, from 65 cases per year before RotaTeq came on the market to 37 cases in 2007, according to researcher Steven Hatch, MD. This year, the figure fell to three, he tells WebMD.
- Researchers at Children's Mercy Hospital in Kansas City, Mo., report that only 62 children were admitted for rotavirus infections in 2008, compared with more than 300 annually the previous four years.
- In North Philadelphia, rotavirus-associated hospitalizations among infants aged 6 to 11 months dropped 94% since rotavirus vaccinations began in 2006, says Irini Daskalaki, MD, of Drexel University College of Medicine.