Most people have a virus hiding in their cells. It’s probably been there for years, and it could reactivate anytime. This virus, varicella-zoster, causes both chickenpox and shingles, a painful rash infection.
Fortunately, vaccines protect against these diseases. But can a vaccine against one infection cause the other?
In a 2023 video clip that recently recirculated on social media, anti-vaccine activist Robert F. Kennedy Jr. said that a California study found that widespread chickenpox vaccination stops chickenpox but later “causes shingles epidemics.”
It was not immediately clear what study Kennedy, now the Trump administration’s Health and Human Services secretary, was referring to, and we didn’t hear back from his Health and Human Services Department. But current available research doesn’t show that widespread chickenpox vaccination efforts increased shingles cases in the U.S.
What else do we know about chickenpox, shingles and the vaccines for both diseases? Here are the basics.
Q: What is chickenpox and who can get it?
Chickenpox is highly contagious. Although it shares symptoms such as fever, headache and fatigue with other infections, chickenpox is best known for its itchy, blistering rash.
A person can become infected by having direct contact with a chickenpox rash or breathing in the air droplets after a chickenpox patient coughs or sneezes.
Anyone who hasn’t had chickenpox or been vaccinated against it is at the highest risk of an infection. The disease is usually more severe for adults.
Q: Who should get the chickenpox vaccine and when?
Doctors recommend the chickenpox vaccine’s two-dose series for anyone who hasn’t had a chickenpox or shingles infection or whose bloodwork shows they don’t have immunity, according to the Children’s Hospital of Philadelphia.
The American Academy of Pediatrics recommends children get the first dose between 12 and 15 months of age and the second dose between 4 and 6 years of age.
The vaccine isn’t 100% effective, but breakthrough infections among vaccinated people are rare and usually milder than what an unvaccinated person would experience.
Adults who get chickenpox are 10 times more likely than children to be hospitalized, so even though chickenpox is often considered a childhood illness, teenagers and adults without immunity should get vaccinated. The American Academy of Pediatrics has guidelines for how people can best catch-up on the doses.
Q: What is shingles and who can get it?
Anyone who has had chickenpox can get shingles. Even after someone has recovered from a chickenpox infection, the varicella-zoster virus remains dormant in certain nerves. Shingles, also called herpes zoster, is a viral infection that occurs when that virus reactivates.
Shingles symptoms include fever, headache, a painful, blistered rash and deep burning or shooting nerve pain. Shingles on the head can infect your eyes, which requires immediate medical attention.
It’s not entirely clear what reactivates the virus, but shingles is more common as people age and their immune systems weaken.
The Centers for Disease Control and Prevention says about 1 in 3 people in the U.S. will have shingles in their lifetime. About 50% of people who live to 85 years old will be infected, according to the Children’s Hospital of Philadelphia.
It’s rare for children to get shingles, but they could effectively catch chickenpox from someone with a shingles infection. A person who has shingles can expose people without immunity to the varicella-zoster virus, which risks spreading chickenpox to anyone unprotected.
Q: Can the chickenpox vaccine cause shingles?
Yes, but early research signals that it’s uncommon.
The chickenpox vaccine teaches the immune system how to fight off infection. The Children’s Hospital of Philadelphia says that the chickenpox vaccine’s weakened virus reproduces in the body far less than the natural virus, which reproduces thousands of times during an infection. The weakened virus, meanwhile, only reproduces about 20 times. This means the vaccine can introduce the virus that causes shingles to the body, but it’s unlikely to cause an infection.
The varicella vaccine wasn’t routinely recommended for children in the U.S. until 1996, so we don’t yet know how this widespread vaccination will impact future shingles cases for vaccinated adults, the oldest of whom are now turning 30.
But one 2019 Pediatrics study found that the annual rates of shingles in children vaccinated against chickenpox were consistently lower than in unvaccinated children. The vaccine virus is also less likely to reactivate than the virus in nature, lab research shows.
Q: Should I vaccinate my child against chickenpox if it can cause shingles?
Unvaccinated children are susceptible to chickenpox infections and all the complications that can follow, including shingles.
Before vaccination became routine in childhood, chickenpox infections hospitalized more than 10,000 people and killed 100 or more each year, according to the CDC. Half of those deaths were children.
“That doesn’t happen anymore,” said Dr. Myron Levin, a pediatric infectious disease professor at the University of Colorado Anschutz. CDC data attributed fewer than 25 deaths to chickenpox infections or complications in 2024 and 2025.
Vaccinating children also affords them important long-term protections, especially against a more severe adult infection.
“You don’t want your child to grow up with the opportunity to get chickenpox in the last 40 or 50 years of their life, because if they do, they’re going to be sick as hell,” Levin said.
A pharmacist displays doses of a vaccine that protects against shingles, at a CVS Pharmacy, Sept. 9, 2025, in Miami. (AP)
Q: Who should get the shingles vaccine and when?
Health officials recommend people 50 and older get the two-dose shingles vaccine, Shingrix. That’s true even if someone previously had shingles or received Zostavax, a former shingles vaccine. They also recommend Shingrix for some immunocompromised people starting at age 19. The two doses should be separated by two to six months.
The vaccine’s common side effects include two to three days of fatigue, muscle ache, fever, shivering, headache, and injection site soreness and redness. Doctors caution that those side effects are minor compared with the pain and risk of long-term complications, including chronic pain, from shingles.
Q: Can the shingles vaccine lead to shingles?
Cases of this happening are extremely rare. The shingles vaccine contains a small part of the virus that causes shingles, not the live varicella-zoster virus, so it cannot cause chickenpox or shingles on its own. In some isolated documented cases, the shingles vaccine appeared to have reactivated the virus, resulting in shingles.
PolitiFact Researcher Caryn Baird contributed to this report.
This story originally appeared on PolitiFact
