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About 4 million cases of chickenpox occur
in the US each year, and 95% of people have had the virus
by the time they reach adulthood. The illness can be severe,
but fatalities are rare.
Chickenpox (varicella) vaccine is recommended
in the United States for children aged 12 to 18 months and
for susceptible older children, adolescents and adults.
CDC researchers report that when the
two vaccines are given less than 30 days apart but not simultaneously,
there is a 2.5-fold increased incidence of
"breakthrough disease," which they define
as a case of chickenpox that occurs more than 42 days after
varicella vaccination.
The
amount of antibody in the blood doesn't increase enough to
confer immunity if one shot follows the other within 30 days.
You need that 30-day
period for the body to respond well to the second
vaccine.
Morbidity
and Mortality Weekly Report November 30, 2001;50:1038-1041
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