Rare Blowel Blockage Linked To Vaccine Has Lower Incidence Than Thought.

2001 OCT 24 - (NewsRx.com & NewsRx.net) -- A study in The Lancet concludes that the risk of intussusception, a bowel obstruction, in infants vaccinated against severe rotavirus diarrhea was substantially lower than previous reports estimated.

The new study is the first to examine the overall risk of intussusception in a large population during the nine-month time period when the vaccine, known as Rotashield, was in use.

Lone Simonsen, PhD, an epidemiologist with the National Institute of Allergy and Infectious Diseases (NIAID), and her colleagues found an overall decrease in hospitalizations for intussusception among infants less than one year old from October 1998 to July 1999, when the vaccine was available, relative to previous comparable time periods going back as far as 1993. They derived their data by examining hospital discharge records from 10 states - home to more than one-fourth of the 3.8 million babies born in the United States each year - in which an estimated 300,000 infants had received the vaccine.

Rotaviruses are the most common cause of severe dehydration and diarrhea in infants and young children, causing some 500,000 physician visits, 50,000 hospitalizations and 20 deaths in the United States each year. In developing countries, rotavirus diarrhea is a leading cause of infant mortality, killing 600,000 to 800,000 infants and young children annually.

After extensive clinical trials proved its safety and efficacy, the first vaccine against severe rotavirus diarrhea, developed by NIAID scientists, was licensed in the United States in August 1998. Two months later, public health officials added the oral Rotashield vaccine to the recommended immunization schedule for healthy infants. The vaccine was to be given in a three-dose series at two, four and six months of age.

Some 1.5 million doses of vaccine were administered to about one million U.S. infants. Hopes were high that it was only a matter of time before the vaccine would reach developing countries, where the need for it is so pressing. But in July 1999, after reports of 15 cases of intussusception among vaccinated children, Rotashield's manufacturer, Wyeth Laboratories, pulled the vaccine off the market. A few months later, U.S. public health officials removed it from the list of recommended vaccines. Though currently licensed by the Food and Drug Administration (FDA), Rotashield is not now available.

Intussusception, diagnosed most often in infancy and childhood, strikes about 2000 infants (1 in every 1900) in the United States in the first year of life. Its incidence begins to rise at about two to three months of life, peaks at four to nine months, and then gradually declines at around 18 months. The condition often resolves by itself, but the blockage can require surgery. In the United States, intussusception is rarely fatal.