BACKGROUND: The FDA has announced a new oral vaccine against the Rotavirus, a highly contagious virus that is the most common cause of severe dehydrating diarrhea in infants and young children. Each year many U.S. infants are hospitalized because of Rotavirus. The vaccine is a liquid given at two, four and six months. Between 2001 and 2004, the developing company -- Merck & Co. -- conducted one of the largest clinical trials of a vaccine ever performed, involving more than 70,000 infants from 70 different countries. The data from those trials demonstrated that the vaccine is both safe and effective.
THE MAKING OF A VACCINE: Whenever a disease-causing micro-organism enters the body, the immune system mounts a defense, producing proteins to fight off the foreign substance. Vaccines stimulate the body's immune system by introducing a weakened form of a particular germ or virus, making the body think it is being invaded by a foreign organism. If a person who has been vaccinated is exposed later to the virus, he or she will be protected because the body already has the necessary antibodies to ward off infection. Merck's new vaccine uses a strain of Rotavirus called WC3, co-infected with other human Rotavirus strains to create the best protection against the disease.
ABOUT ROTAVIRUS: Rotavirus is an infection of the digestive tract, caused by wheel-shaped viruses that infect the intestine. Infection begins with fever and vomiting, followed by diarrhea, which can last anywhere from 3 to 9 days. Those with severe diarrhea, especially children, can lose body fluids so quickly they become dangerously dehydrated. Apart from vaccination, there is no other means of completely eliminating the spread of infection. But maintaining strict hygienic practices can reduce it, even if soaps and cleaners don't kill the virus. For instance, wash hands after using the bathroom, changing diapers, and before preparing or serving food.
The American Society for Microbiology contributed to the information contained in the TV portion of this report.