(RxWiki News) Sometimes one public health initiative can have unintended consequences. Could this have happened with the chickenpox vaccine and shingles?
Apparently not, according to a recent study that found shingles rates did not increase as a result of the chickenpox vaccine.
Shingles and chickenpox are both caused by the same virus. It's called varicella zoster with chickenpox and herpes zoster with shingles.
Shingles usually occurs in individuals who had chickenpox when they were younger. High stress or a weakened immune system can sometimes cause the dormant virus to flare up again.
"Discuss vaccinations with your doctor."
This study, led by Craig M. Hales, MD, MPH, of the US Centers for Disease Control and Prevention (CDC), looked at whether the arrival of the chickenpox vaccine had any effect on rates of shingles.
Small exposures to chickenpox throughout life were thought to reduce people's chances of experiencing shingles by keeping their immunity levels against the virus higher. There were therefore concerns that reducing chickenpox through vaccination might cause older adults to experience more shingles.
Even though shingles rates have increased in the past few decades, this study found that the increase was not related to the chickenpox vaccine, introduced in 1996.
Dr. Hales and colleagues investigated Medicare data for 2.8 million patients, aged 65 and older, from 1992 through 2010.
These researchers found that 281,317 cases of shingles occurred during that time period.
The rate of shingles over those 18 years increased about 39 percent, from 10 cases per 1,000 people a year in 1992 to 14 cases per 1,000 people a year in 2010.
However, the increase started occurring before 1996, when the chickenpox vaccine was added to the CDC childhood immunization schedule.
In fact, the researchers found no change in the overall rate of shingles from one state to another between 1997 and 2010 based on those states' rates of chickenpox vaccination coverage.
In addition, the researchers reported that shingles cases also rose in a number of other countries that do not use the chickenpox vaccine.
The researchers also found that shingles cases were a little higher among women than among men and a little lower among blacks and Hispanics than among whites.
Currently, the researchers could not find an explanation for why the rates of shingles increased.
This study was published December 3 in the Annals of Internal Medicine. The research was funded by the CDC. The authors reported no conflicts of interest.