If you're pregnant or have a newborn, your baby may be lucky enough to never experience rotavirus, a nasty diarrheal illness that affects almost all children before age 5, thanks to a new vaccine called RotaTeq. The vaccine was approved by an advisory committee for the Centers for Disease Control in February 2006 for inclusion in the standard immunization schedule for infants, and pediatricians will likely begin administering it in three doses (at 2, 4, and 6 months of age) as soon as this month, says Joseph Bocchini, M.D., a member of the American Academy of Pediatrics (AAP) Committee on Infectious Diseases. RotaTeq was tested in the largest clinical trial ever performed for an immunization -- 72,000 infants in the United States and other countries -- and was found to prevent 98 percent of severe cases of the illness. RotaTeq is given by mouth, and side effects may include an upset stomach and loose stools. Talk to your pediatrician about whether your baby should receive this new immunity-building vaccine.