The widespread use of a vaccine against a germ that causes gastrointestinal infections in infants and young children has been a resounding success in the United States, a new study suggests.
Most common cause of severe acute gastroenteritis
A team led by Dr. Eyal Leshem of the U.S. Centres for Disease Control and Prevention reports a big drop in the number of young children hospitalised with gastroenteritis since routine immunisation against rotavirus was launched in 2006.
"Rotavirus is the most common cause of severe acute gastroenteritis – vomiting and severe diarrhoea – among children across the world," said one expert, Dr. Roya Samuels, a paediatrician at Cohen Children's Hospital of New York in New Hyde Park.
Read: Nausea and vomiting
But two vaccines – Rotateq and Rotatrix – can prevent up to 87 percent of all rotavirus illnesses occurring during a baby's first year, said Samuels, who was not involved in the new study.
In the new research, Leshem's team tracked data from 26 states. They found a steep decline between 2008 and 2012 for hospitalisations for gastroenteritis among children younger than 5 years of age.
Before rotavirus vaccination was implemented, 76 out of every 10,000 children under 5 was hospitalised for gastroenteritis from any cause, the researchers noted. However, after widespread vaccination began, that rate declined by 31 percent in 2008, by 33 percent in 2009, by 48 percent in 2010, and by 55 percent in 2012.
"Herd immunity" probably playing a big role
There were similar rate declines among girls and boys, across all racial/ethnic groups, and in all age groups, the CDC team said.
The largest decreases occurred among children ages 6 months to 23 months, according to the study published in the Journal of the American Medical Association.
Before rotavirus vaccination began, the rate of hospitalisation for gastroenteritis directly linked to rotavirus among children younger than 5 years was 16 cases per 10,000 children. However, after vaccination began, rates fell by 70 percent in 2008, 63 percent in 2009, 90 percent in 2010 and 94 percent in 2012.
The authors say that individual babies are protected by the vaccine, of course, but "herd immunity" is probably playing a big role as well. Herd immunity occurs when a child's chance of coming into contact with a germ drops because so many other people are also immune to the bug, and are therefore not passing it on.
Read: Immune response
"The vaccine has truly been amazing if you look at the numbers," said another expert, Dr. Tuvia Marciano. He directs paediatric endoscopy at Winthrop-University Hospital in Mineola, New York.
"There was data published previously on the effect of the vaccine," Marciano said, "and we know it drastically reduced admissions for kids sick with rotavirus and for kids sick with gastroenteritis." That's great news, he added, since "gastroenteritis and dehydration makes up a large percentage of [paediatric] hospital admissions."
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