Research has shown that shingles, a viral infection caused by a reactivation of the chickenpox virus, is linked to an increased risk of stroke. In a recent study, researchers found that Zoster Vaccine Live, a type of shingles vaccine, may also prevent stroke in some older adults.

Shingles usually occurs in adults over the age of 50. In the United States, more than 99% of people aged 40 years or older carry the dormant chickenpox virus, also referred to as the varicella-zoster virus. As individuals age and experience other health conditions, the risk for developing shingles increases as well. Shingles is painful and can cause skin blisters, as well as other complications.

"One in 3 people who have had chickenpox develop shingles in their lifetime," said Quanhe Yang, PhD, lead study author and senior scientist at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, in a press release. "The Zoster Vaccine Live helps to prevent shingles and reduces the risk for shingles by about 51%. But its effect declines with increased age, about 64% in people 60-69 years, about 41% for ages 70-79 years, and about 18% in those 80 years or older."

During the study, researchers analyzed the Medicare health records of more than 1 million Medicare fee-for-service beneficiaries age 66 or older who did not have a history of stroke and who were vaccinated with the Zoster Vaccine Live during the period between 2008 and 2014. The researchers followed these individuals for an average of nearly 4 years.

In addition, during that 4-year period, the researchers followed the same number of Medicare fee-for-service beneficiaries who did not receive the shingles vaccine. To assess the effect of the vaccine on stroke risk, the researchers controlled for age, gender, race, medications, and co-existing health conditions.

According to the resulting research presented at the American Stroke Association's International Stroke Conference 2020 in February, receiving the shingles vaccine lowered the risk of stroke by approximately 16%, lowered the risk of ischemic (clot-caused) by approximately 18%, and lowered the risk of hemorrhagic (bleeding) stroke by approximately 12%.

The protection provided by the vaccine was also the strongest among people aged 66 to 79 years. Additionally, among those under the age of 80, the shingles vaccine was found to reduce the risk of stroke by nearly 20%, and in those older than 80 years of age, by approximately 10%.

"The reason for increased risk of stroke after a shingles infection may be due to inflammation caused by the virus. Approximately 1 million people in the United States get shingles each year, yet there is a vaccine to help prevent it," Yang said in the press release. "Our study results may encourage people ages 50 and older to follow the recommendation and get vaccinated against shingles. You are reducing the risk of shingles, and at the same time you may be reducing your risk of stroke."

This research was conducted initially in the period before 2017 when the only shingles vaccine available was Zoster Vaccine Live. The newest shingles vaccine, Adjuvanted, Non-Live Recombinant Shingles Vaccine, became available in 2017.

The researchers noted that future studies will be necessary to confirm the association between Zoster Vaccine Live and stroke, as well as to assess any association between Adjuvanted, Non-Live Recombinant Shingles Vaccine and risk for stroke.

REFERENCE
Shingles vaccine may also reduce stroke risk. Dallas, TX: American Heart Association; February 12, 2020. eurekalert.org/pub_release