The Shingrix shingles vaccine carries a slightly higher risk for Guillain-Barré syndrome than its older competitor, according to a new study. Photo by huntlh/Pixabay
Older adults who receive the Shingrix shingles vaccines are more than twice as likely to develop Guillain-Barré syndrome compared with those given the older Zostavax product, a study published Monday by JAMA Internal Medicine found.
However, the risk for Guillain-Barré, an immune disorder that damages the nervous system and causes muscle weakness, is rare with both shots, the data showed.
Among more than 1.3 million adults given the Shingrix vaccine, manufactured by GlaxoSmithKline, 15 cases of Guillain-Barré were identified, according to researchers from the Food and Drug Administration and Centers for Disease Control and Prevention.
In comparison, nine cases of Guillain-Barré were reported among more than 1.8 million people given the Zostavax vaccine, manufactured by Merck.
Merck stopped manufacturing the vaccine in the United States in July 2020 and its sale and use was discontinued in the United States as of Nov. 18, 2020.
“Our current findings confirm an increased risk of Guillain-Barré syndrome following [Shingrix] vaccination in the Medicare population aged 65 years and older,” researchers wrote in the new study.
However, “the increased risk of Guillain-Barré syndrome following [Shingrix vacination] should be considered in the context of the benefits of the vaccine,” they said.
Shingles, also known as zoster or herpes zoster, is a viral disease that causes a painful skin rash with blisters.
Although common — about one in three people in the United States will develop it in their lifetimes — illness can cause serious complications in older adults, including increased risk for stroke, the CDC said.
Shingles is caused by varicella zoster virus, which also causes chickenpox, according to the CDC.
After a person recovers from chickenpox, the virus stays inactive in their body, but it can reactivate later, causing shingles.
Currently, the CDC recommends that healthy adults age 50 and older get two doses of the shingles vaccine separated by two to six months.
Shingrix, which received FDA approval in 2017, is considered the vaccine of choice, given that it is up to 85% more effective at preventing shingles than Zostavax, studies indicate.
For this study, the FDA and CDC compared data on more than 3.1 million people — most were in their 70s — who received either Shingrix or Zostavax.
The more than 1.3 million people given Shingrix were vaccinated between Oct. 1, 2017, and Dec. 31, 2018, while the roughly 1.8 million who received Zostavax did so between Oct. 1, 2012, and Sept. 30, 2017.
Fifteen of those given Shingrix developed Guillain-Barré syndrome within 42 days of vaccination, for a rate of 0.29 cases per 1 million shots administered, the data showed.
The nine people who received Zostavax and were diagnosed with Guillain-Barré syndrome within 42 days, for a rate of 0.12 cases per 1 million shots administered.
“Patients and clinicians should be aware of the risk of Guillain-Barré syndrome and consider the benefits of avoiding zoster with an efficacious vaccine,” they wrote.