Immunity can fade after first injection, so second shot now recommended
FRIDAY, Aug. 8 (HealthDay News) -- When the vaccine against chickenpox was introduced in the United States in 1995, medical experts hoped it would be a one-shot deal, with a single injection about the time of a child's first birthday giving lifelong immunity.
Now, experts are learning that's not so. They've found that the protection from a single immunization fades over time, and that a booster shot is needed if you want your child to have the best chance at lifelong protection from chickenpox.
The experts reached that conclusion after examining 10 years of data and the effects of the vaccine on more than 11,000 people who got the shot between 1995 and 2004. Of those individuals, 9.5 percent, or 1,080, experienced so-called "breakthrough disease," researchers reported last year in the New England Journal of Medicine.
"The breakthrough was mild," said Dr. Robert Frenck Jr., a professor of pediatrics at Cincinnati Children's Hospital and a member of the American Academy of Pediatrics' committee on infectious diseases.
Chickenpox, which is caused by an infection by the varicella-zoster virus, typically starts as a rash on the face that spreads. The rash begins as red bumps that become blisters. Often a child can get hundreds of blisters, which crust over and fall off the body in a week or two.
The children who suffered "breakthrough" chickenpox typically got fewer lesions, Frenck said, perhaps 20 to 50. Still, schools and day-care centers would not welcome them back until the sores had dried or crusted, because the disease can spread easily from person to person.
Based on those findings, experts from the U.S. Centers for Disease Control and Prevention and elsewhere are now recommending that a second booster shot be given to children between 4 and 6 years of age.
There is some leeway in that schedule
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