Jan. 3, 2011 -- The chickenpox vaccine prevented more than 50,000 hospitalizations from 2000 to 2006, according to new data published in the February issue of Pediatrics.
This time frame is known as the one-dose chickenpox (varicella) vaccination era. In 2006, however, the CDC began recommending two doses of the vaccine.
“It is expected that the implementation of this recommendation will lead to additional declines in varicella incidence and hospitalization rates,” conclude study researchers led by Adriana S. Lopez, MHS, of the CDC, in Atlanta.
Before the vaccine was first licensed by the FDA in 1995, there were 11,000 people hospitalized with chickenpox each year and 100 people died as a result of the disease, according to the CDC.
Today, the American Academy of Pediatrics (AAP) and the CDC recommend that children who have never had chickenpox receive their first dose of the chickenpox vaccine at 12-15 months and their second at 4-6 years. Those aged 13 and older who have not had chickenpox or received the vaccine should receive the two doses at least 28 days apart. A combination measles, mumps, rubella, and varicella (MMRV) vaccine was also licensed in 2005.
Chickenpox Hospitalizations Reduced by 71%
Researchers analyzed data from the National Hospital Discharge Surgery and Nationwide Inpatient Sample from 1988 to 2006. Rates of hospitalization from chickenpox decreased by 71% during this time period. This translates into about 50,000 fewer hospitalizations from chickenpox during the one-dose vaccine era.
The sharpest decrease was seen in children younger than 10, the study showed.
Hospitalization rates remained highest among children younger than 4, but even these numbers were 72% lower than they were during the pre-vaccination era of 1988 to 1995.
There had been some concern that vaccinating children may leave adults who had never had chickenpox vulnerable to more severe infections. This has not been borne out, the new study shows.
Owing to herd immunity, chickenpox-related hospitalizations did not increase in people 20 and older once varicella vaccination had been implemented. Herd immunity refers to vaccinating the eligible masses to keep infections out of circulation; thereby protecting those who can’t get vaccinated, such as people with certain types of cancer.
Most Parents Embrace Chickenpox Vaccine
“This study confirms that proponents of this vaccine were right,” says James McAuley, MD, a specialist in pediatric infectious disease Rush University Medical Center in Chicago. “The new study pretty clearly proves that the chickenpox vaccine cuts down the number of kids who have been hospitalized for varicella.”
He recalls that there was a lot of push-back from parents when this vaccine was first rolled out.
But “we have seen almost no side effects with this vaccine in the scientific community and in the world of parent concern so this has limited their push back,” he says.
Henry Bernstein, MD, chief of general pediatrics at the Cohen Children's Medical Center in New Hyde Park, N.Y., and a member of the AAP’s Committee on Infectious Diseases, agrees.“There has been an increasing acceptance of this vaccine by families and the immunization rates for varicella continue to go up,” he says.
He expects to see even greater reductions in hospitalizations now that the vaccine is given as two doses.
This double-dose regimen will increase protection to about 99%, he says. This means more protection for more people, and fewer hospitalizations and deaths from chickenpox, Bernstein says.
“It is truly remarkable the impact that universal immunization with chickenpox vaccine has achieved,” he says.