Second Dose of Vaccine Cuts Chickenpox Cases Even More, Study Finds
Kids and adults benefit from children receiving both recommended immunizations, researcher says
Infections in these sites dropped dramatically between 2006 and 2010. The Antelope Valley site had 76 percent fewer cases of chickenpox in 2010 than they did in 2006. West Philadelphia saw a 67 percent decline in the same time period. Both sites had a 98 percent decline in the incidence of chickenpox from 1995 to 2010.
Of those who came down with chickenpox between 2006 and 2010 in the study sites, just 7.5 percent had been vaccinated with two doses. Slightly less than two-thirds had received one vaccination. Most of those who got the chickenpox even though they'd been vaccinated had a mild case with fewer than 50 lesions on their bodies. The study also found that hospitalization rates dropped even further.
During 2007 to 2010, just 12 chickenpox outbreaks occurred within the California site compared with 47 outbreaks during 2003 to 2006, and 236 outbreaks during 1995 to 1998, according to the study.
Civen said all of these declines can be attributed to the additional dose of vaccine. "This is solely about getting that second dose," she noted.
"The varicella vaccine is very effective and safe. It helps those who get the vaccine and others who can't get the vaccine, but are highly susceptible to infection, such as immunocompromised adults," she said.
An expert not involved with the study found its results convincing.
"I think the data is pretty clear that the second dose is having a dramatic effect," said Dr. Thomas Murray, a pediatric infectious disease specialist and associate professor of medical sciences at Quinnipiac University's Frank H. Netter MD School of Medicine in North Haven, Conn.
"The second dose in the varicella vaccine program is very effective in reducing varicella in the general population," he said.
The CDC recommends that children under 13 years get two doses of the chickenpox vaccine: one between the ages of 12 months and 15 months, and the second dose between the ages of 4 and 6 years.
People aged 13 and older who've never had chickenpox or the vaccine should get two doses, at least 28 days apart, the CDC says.