A recent study suggests the shingles vaccine, in addition to preventing herpes zoster infection, may be associated with slower biological aging in older adults. Research also indicates potential links between vaccination and reduced risks of conditions such as dementia, stroke, and heart attack.
Shingles Vaccine and Biological Aging: The USC Study
Researchers Jung Ki Kim and Eileen Crimmins from the University of Southern California conducted an observational study on over 3,800 U.S. participants aged 70 or older. Published in the Journals of Gerontology, their findings indicate significant associations between vaccination and markers of aging.
Individuals who received the shingles vaccine after age 60 performed better on composite measures of biological aging compared to unvaccinated individuals.
Vaccinated participants also exhibited biological markers associated with lower inflammation and a slower rate of molecular, overall biological, genetic, epigenetic, and transcriptomic aging. These associations remained consistent even after accounting for demographic and health differences between the groups.
Biological age refers to the health and functional age of a person's body at a molecular level, distinct from chronological age.
Eileen M. Crimmins, a professor of gerontology at the University of Southern California, stated that slowing biological aging could extend both overall lifespan and years of healthy life, characterized by improved physical and cognitive function.
Beyond Shingles: Potential Mechanisms and Wider Health Advantages
While the study is observational and does not establish definitive proof of causation, its findings align with other research suggesting wider health advantages of the shingles vaccine in later life.
Researchers propose that by helping to reduce background inflammation, potentially through preventing the reactivation of the varicella-zoster virus, the vaccine might support healthier aging. This mechanism could influence biological systems beyond direct infection control, potentially addressing age-related conditions like heart disease and cognitive decline. The precise biological mechanisms require further investigation.
Beyond its role in preventing shingles and potentially slowing biological aging, emerging evidence suggests the shingles vaccine may also reduce the risk of dementia, stroke, and heart attack. Older studies indicated an association between shingles and an increased risk of dementia. Newer research on the Shingrix vaccine shows promising results regarding dementia risk reduction, according to Emily Rayens, a postdoctoral fellow at Kaiser Permanente Southern California.
The shingles vaccine is positioned as a potential component in strategies aimed at addressing age-related decline. Other medications currently under examination for their potential to slow biological aging include the type 2 diabetes drug metformin, the immunosuppressant rapamycin, and rilmenidine, a blood pressure medication.
Understanding Shingles (Herpes Zoster)
Shingles, also known as herpes zoster, is a viral infection caused by the reactivation of the varicella-zoster virus (VZV), the same virus responsible for chickenpox. After an initial chickenpox infection, the virus remains dormant in nerve roots, specifically in the dorsal root ganglion near the spinal cord. It can reactivate later in life, typically after age 50, causing inflammation of the nerve and a painful rash. Approximately one in three people in the United States will experience shingles in their lifetime.
Symptoms
- Pain (often the initial symptom)
- Sensitivity to touch
- Itching and burning sensation
- Red rash with blisters (commonly appearing as a distinctive stripe on one side of the body)
- Some individuals may also experience fever, headache, and fatigue.
Complications
- Postherpetic neuralgia (PHN): Persistent nerve pain that can last for months or years, affecting 10-18% of shingles patients, with risk increasing with age.
- Hospitalization occurs in approximately 1-4% of individuals with shingles.
- Older adults and those with suppressed immune systems are at higher risk for severe cases.
- The Centers for Disease Control and Prevention (CDC) reports fewer than 100 annual shingles-related deaths in the U.S.
- Other potential severe complications include pneumonia, encephalitis, and hearing or vision loss.
Risk Factors and Reactivation
The exact triggers for VZV reactivation are not fully understood, but a weakened immune system, intense physical or emotional stress, and certain medical conditions like diabetes and asthma can increase the risk. Trauma to the skin can also cause symptoms to emerge in the affected area.
Transmission
The virus can spread through contact with fluid in shingles blisters or by inhaling virus particles released from blisters. An individual is infectious from the time blisters appear until they are dry and scabbed, typically seven to ten days. Blisters generally clear within two to four weeks. Individuals who have never had chickenpox would contract chickenpox upon exposure, not shingles.
The Shingles Vaccine: Shingrix
The current shingles vaccine available in the U.S. and UK is Shingrix. This vaccine is designed for the immune needs of older adults.
Efficacy and Benefits
- According to the CDC, Shingrix is over 90% effective in preventing shingles in adults aged 50 and older with healthy immune systems.
- If a vaccinated individual contracts shingles, the vaccine can reduce the disease's severity.
- Vaccination can help prevent future occurrences in those who have previously had shingles and reduces the risk of severe complications like PHN.
Recommendations
- The CDC recommends two doses of Shingrix for adults aged 50 and older, administered two to six months apart.
- The agency also recommends vaccination for adults aged 19 and older with weakened immune systems, who can receive the second dose one to two months after the first.
- Booster doses are not currently recommended.
Vaccination Rates
Despite the prevalence of shingles, U.S. vaccination rates for adults over 60 remain low, approximately 35-36%.
Contraindications
Individuals with current shingles, pregnant individuals, or those with a history of allergic reaction to Shingrix are advised against vaccination. Current recommendations do not advise vaccination for healthy individuals before age 50 due to a lack of evidence for early benefit and potential insurance coverage issues.
Side Effects
No serious side effects are associated with Shingrix, according to the CDC. Temporary side effects may occur, including:
- Pain and swelling at the injection site (typically resolving within a day).
- Flu-like symptoms, such as a low-grade fever and aches (may last for a few days). These symptoms are generally more common after the first dose and in younger adults.
Effectiveness Duration and Coverage
Studies suggest Shingrix effectiveness ranges from four to eleven years, with efficacy declining if only one dose is received. In the U.S., most insurance plans and Medicare Part D cover the vaccine at no cost for eligible individuals.
Future Research
Future, long-term studies are needed to fully ascertain the extensive health implications of the shingles vaccine, particularly concerning its associations with biological aging and other age-related conditions.