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 said.
"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 otherwise healthy.
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 65 and older was recently introduced to prevent shingles.
To learn about chickenpox in children, see the Nemours Foundation.
SOURCES: Joseph Bocchini, M.D., chief of pediatrics, Health Sciences Center, Louisiana State University, Shreveport, La.; Adriana Lopez, M.H.S., epidemiologist, viral diseases division, National Center for Immunizations and Respiratory Diseases, U.S. Centers for Disease Control and Prevention, Atlanta; February 2011, Pediatrics; Infectious Diseases Society of America
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