The chickenpox vaccine may also significantly reduce a child’s risk of shingles, according to new study.
Researchers reviewed the medical records of more than 6 million children, and found that those who did not get the chickenpox vaccine were over four times more likely to develop shingles before age 17 than those who were vaccinated according to NBC News. The study was published in the journal Pediatrics.
Chickenpox and shingles are caused by the same virus, the varicella zoster virus. After a person is infected with chickenpox, the virus goes into hiding in the body and can reactivate later, causing shingles. While shingles is most commonly seen in people aged 50 and up who had chickenpox as children, it does sometimes occur in children and teens.
The results of this huge study indicate that “there is a dual benefit of vaccination,” said the study’s lead author, Sheila Weinmann, a senior investigator at Kaiser Permanente Northwest Center for Health Research. “The take-home message for parents is that the varicella vaccination reduces risk of shingles as well as chickenpox in children.”
According to the experts, this means that the adults who got vaccinated against chickenpox as kids won’t have to worry as much about getting shingles when they hit their 50s. The researchers looked at the medical records of more than 6 million children and teenagers. About 3 million had received the chickenpox, or varicella vaccine while about 3 million had not.
During the 12-year study period, the researchers found that 9,044 of the unvaccinated children developed shingles, compared with 5,339 of the vaccinated children.
Weinmann said that there are three possible explanations for why children who get the chickenpox vaccine would get shingles. First, you could be infected with a different strain of chickenpox virus after being vaccinated, and the vaccine doesn’t protect against that strain. “No vaccine is 100 percent effective,” Weinmann said. Second, you may have already had the chickenpox before getting vaccinated, but the case was too mild to notice, she said. Finally, “you could get shingles from the live attenuated virus in the vaccine,” she said.
An attenuated virus, such as the one used in the varicella vaccine, is a strain that has been engineered to be so weakened that it can’t make you sick when you get the vaccine, said Dr. Tina Tan, a professor of pediatrics at Northwestern University’s Feinberg School of Medicine and an infectious disease specialist at the Robert H. Lurie Children’s Hospital. It’s just similar enough to the regular virus to alert your immune system to make antibodies that can fight the virus in the future, but apparently, in a small number of cases, that weakened form of the virus could to lead to shingles, Tan told NBC News.
But the study should reassure parents that it’s highly unlikely this would happen.
The research “proves that the varicella vaccine really does prevent [shingles],” said Tan, who was not involved with the study. “There was some hint of this when they did clinical trials, but with millions of children, this study presents really strong evidence.”