WEDNESDAY, Jan. 5 (HealthDay News) -- The one-dose chickenpox
vaccine dramatically cut the number of chickenpox-related
hospitalizations in the United States for the first half of the
past decade, according to a new study.
And a second study has found that the two-dose version of the
vaccine, first recommended by the U.S. Centers for Disease Control
and Prevention in 2006, may offer youngsters even better
Chickenpox, caused by the varicella zoster virus, can result in
dehydration, bacterial skin infections and, in rare cases, death.
Vaccination for chickenpox became available in the United States in
1995. The so-called "one-dose era" ended in 2006 when a federal
advisory panel recommended two doses of the vaccine be given -- the
first at ages 12 to 15 months, and the second at ages 4 to 6
According to researchers, the one-dose vaccine program, run by
the CDC and state and local governments, prevented about 50,000
hospitalizations in the United States from 2000 to 2006.
"Our study shows that the vaccination program has been successful in reducing varicella-infection hospitalizations not only among the targeted population of 10 years and under, but also has resulted in a 65 percent decline in persons greater than 20 years of age during the one-dose era," said study co-author Adriana Lopez, an epidemiologist in the division of viral diseases in the CDC's National Center for Immunizations and Respiratory Diseases.
During the one-dose era, the annual hospitalization rate for
chickenpox decreased 70 percent for children under 20 years old and
65 percent for those aged 20 and older, according to the report in
the February issue of
The study analyzed medical records from two national databases,
the National Hospital Discharge Survey and the Nationwide Inpatient
A second study, published in the Feb. 1 issue of the
Journal of Infectious Diseases, looked at the clinical effectiveness of giving two versus one dose of the vaccine. In their study, researchers led by Dr. Eugene D. Shapiro of Yale University identified 71 cases of chickenpox in children aged 4 or older in Connecticut.
None of the youngsters who came down with the illness had
received the two-dose course of the vaccine, while 93 percent had
received one dose and 7 percent had not been vaccinated.
In further study, Shapiro's team compared children who received
two doses of the vaccine to those who received one dose and found
that the effectiveness rates were 98.3 percent and 86 percent,
In other words, "the odds of developing varicella were 95
percent lower in children who had received two doses of the vaccine
compared with those who had received only one," Shapiro said in a
news release from the Infectious Diseases Society of America. His
team believes the study findings support the CDC's recommendation
for the two-dose regimen.
Vaccination for varicella is recommended for everyone who has
not had chickenpox, and most states require it before children can
enter school or daycare. Older people are more likely to get a
severe case because of their weaker immune systems, said Lopez.
"Even if you have had chickenpox in the past, it's safe to get vaccinated again," said Lopez, adding that the vaccine "has a very safe profile."
According to the
Pediatrics study, the benefits of even the one-dose
vaccination program translated not only into less illness and
suffering, but monetary savings as well. During 2009, chickenpox
vaccination resulted in savings of more than $1 billion in medical
and societal costs, mostly because parents did not need to stay
home from work to care for sick children, Lopez said.
According to another expert, the one-dose study points to the
social benefits of the vaccination program.
"I think people should feel very confident that the vaccine is working as expected," said Dr. Joseph Bocchini, chief of pediatrics at the Louisiana State University Health Sciences Center. "It protects children from serious disease, and reduced the rate of hospitalizations."
Bocchini said the
Pediatrics study was strong because it relied on two sources
for the data, even though there was a small difference between
their results. The trend is the same for both databases, he
"It's not unexpected, but it's nice to know that individuals who are older and not part of the vaccination campaign are also being protected by reducing the circulation of the virus in the community," said Bocchini.
Although people with compromised immune systems are at higher
risk than healthy people of developing complications from
chickenpox, Bocchini pointed out that 70 percent of hospital
admissions during the one-dose era were for people who were
Lopez and her team are also looking at whether the vaccination
program affects shingles, an infection that occurs in older adults
when the varicella virus activates after years of dormancy. So far,
no effect has been seen, said Lopez.
Shingles produces a painful rash, usually on one side of the
chest, but sometimes on one side of the head, neck or face. A
vaccine for those aged 60 and older was recently introduced to
To learn about chickenpox in children, see
the Nemours Foundation.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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