July 25, 2011 -- Chickenpox deaths in the U.S. have been nearly eliminated thanks to widespread use of the varicella vaccine, according to a new CDC study.
Researchers found chickenpox deaths have dropped by 88% overall and by 97% among children and adolescents since 1995, when the varicella vaccine program began in the U.S. Before the varicella vaccine became available, chickenpox was responsible for about 100 deaths and 11,000 hospitalizations each year.
"The impressive decline in varicella deaths can be directly attributed to successful implementation of the 1-dose vaccination program," write study researcher Mona Marin, MD, of the CDC, and colleagues in Pediatrics. "With the current 2-dose program, there is potential that these most severe outcomes of a vaccine-preventable disease could be eliminated."
A second varicella vaccine dose given at the age of 4 to 6 years was added to national vaccination recommendations in 2006. The first dose is given at the age of 12 to 18 months.
Since 2005, the varicella vaccine has also been available as part of a combination vaccine that offers protection against measles, mumps, rubella, and varicella, known as the MMRV.
Most cases of chickenpox are mild, but it can be life-threatening in rare cases, especially among those with weakened immune systems such as infants and the elderly.
In the study, researchers analyzed national data on deaths for which varicella was listed as an underlying or contributing cause from 2002 to 2007.
Previous studies have reported a 66% overall decline in chickenpox deaths in the first six years of the vaccination program from 1995 to 2001. Researchers say that since then vaccination coverage has increased substantially.
The results show that during the 12 years of the one-dose varicella vaccination program the annual death rate from chickenpox decreased by 88%. The decline was evident in all age groups, but especially among children and adolescents under age 20 (97% decline) and adults under 50 (96% decline).
Researchers say the reduction in chickenpox deaths found in this study is higher than previously estimated and exceeds the cost-effectiveness anticipated by the one-dose program.
"However, this should be interpreted bearing in mind that varicella causes few deaths and that the main benefit of the vaccination program comes from a reduction of lost work and medical care associated with cases and severe complications," write the researchers. "Nevertheless, varicella deaths are a powerful reminder of the importance of vaccination for prevention."