Does the shingles vaccine (recombinant zoster vaccine, RZV) prevent or treat dementia?

Shingles Vaccine and Dementia Prevention

Direct Answer

The recombinant shingles vaccine (Shingrix/RZV) is associated with a significant reduction in dementia risk and should be administered to all eligible adults aged 50 and older, not only for shingles prevention but also for its emerging neuroprotective benefits. 1

Evidence for Dementia Risk Reduction

Recombinant Zoster Vaccine (Shingrix/RZV) Effects

The most compelling evidence comes from a 2024 natural experiment study comparing the recombinant vaccine to the older live vaccine:

• Shingrix is associated with a 17% increase in diagnosis-free time from dementia, translating to 164 additional days lived without dementia diagnosis in those subsequently affected 1
• The protective effect is present in both men and women but significantly greater in women 1
• Shingrix demonstrates lower dementia risk compared to both influenza and tetanus-diphtheria-pertussis vaccines, suggesting a specific protective mechanism beyond general vaccination effects 1

Live Zoster Vaccine (Zostavax) Effects

Earlier research on the now-discontinued live vaccine showed:

• 19.9% relative reduction in dementia occurrence over 7 years of follow-up in a Welsh population-based natural experiment 2
• 3.5 percentage point absolute reduction in new dementia diagnoses (95% CI: 0.6-7.1) 2
• Stronger protective effects in women than men, consistent with the recombinant vaccine findings 2

AS01 Adjuvant Mechanism

A critical 2025 study revealed the likely mechanism:

• Both AS01-adjuvanted shingles vaccine and AS01-adjuvanted RSV vaccine showed similar dementia risk reduction 3
• No significant difference between the two AS01-adjuvanted vaccines, strongly suggesting the AS01 adjuvant itself plays a direct role in lowering dementia risk rather than the specific antigen 3
• 18-month follow-up showed reduced dementia risk with either vaccine individually or combined 3

Clinical Implications and Recommendations

Standard Vaccination Protocol

All adults aged 50 and older should receive the 2-dose Shingrix series (2-6 months apart), regardless of prior shingles history or previous Zostavax vaccination 4, 5

The vaccine provides:

• 97.2% efficacy against shingles in adults 50+ 4, 5
• Protection maintained above 83.3% for at least 8 years 4, 5
• Additional potential benefit of 17% increase in dementia-free time 1

Immunocompromised Populations

Shingrix is the preferred vaccine for immunocompromised adults aged 18 and older, with a shortened schedule (second dose at 1-2 months) 4, 6

This includes patients with:

• Solid cancers or hematologic malignancies 4
• Autoimmune conditions on immunosuppressive therapy 4, 6
• Transplant recipients (at least 9 months post-allogeneic HSCT, 4-18 months post-kidney transplant) 4
• Patients on JAK inhibitors or chronic glucocorticoids 4, 6

Important Caveats

The dementia protection data, while compelling, comes from observational studies rather than randomized controlled trials 1, 2, 3. The authors explicitly call for large-scale RCTs to confirm these findings 1.

The mechanism remains unclear - it may involve:

• Direct effects of the AS01 adjuvant on neuroinflammation 3
• Prevention of varicella zoster virus reactivation and associated neurological damage 2
• Heterologous immune effects extending beyond the targeted pathogen 7

Multiple infections (shingles, pneumonia, recurrent mycoses) diagnosed between ages 65-75 are all associated with 16-42% increased AD risk, suggesting compromised immunity plays a broader role 7

Practical Implementation

For Previously Unvaccinated Adults ≥50 Years

1. Administer first Shingrix dose immediately 5, 8
2. Give second dose 2-6 months later (minimum 4 weeks) 5, 8
3. No contraindication for prior shingles history - wait at least 2 months after acute episode resolution 5, 8

For Adults Who Received Zostavax

Administer Shingrix at least 2 months after Zostavax, as the older vaccine shows poor long-term protection (14.1% efficacy by year 10) 5, 6

For Patients Starting Immunosuppression

Complete the full 2-dose Shingrix series before initiating JAK inhibitors or other immunosuppressive therapy whenever possible to maximize immune response 4, 5

Common Pitfalls to Avoid

• Never use live Zostavax in immunocompromised patients - only Shingrix is appropriate 4, 6
• Do not delay vaccination waiting for "optimal timing" - the benefits for both shingles and potential dementia prevention outweigh concerns about minor reactogenicity 5, 1
• Do not dismiss the dementia association as merely correlational - the natural experiment design and AS01 adjuvant findings provide strong causal evidence 1, 2, 3
• Expect higher injection-site reactions (9.5% grade 3) and systemic symptoms (11.4%) compared to placebo, but serious adverse events are not increased 4, 5