What is the efficacy of the shingles (Herpes Zoster) vaccine?

Shingles Vaccine Efficacy

The recombinant zoster vaccine (Shingrix/RZV) is highly effective, demonstrating 97.2% efficacy in preventing herpes zoster in adults aged 50 years and older, with protection maintained above 83.3% for at least 8 years. 1

Efficacy by Age Group

• Adults aged 50+ years: RZV demonstrates 97.2% vaccine efficacy against herpes zoster in the pivotal ZOE-50 trial 1
• Adults aged 70+ years: Efficacy remains robust at 89.8%, showing minimal decline with advancing age 2
• Real-world effectiveness: A large Medicare cohort study found 70.1% effectiveness for the complete 2-dose series, which is lower than clinical trial estimates but still represents substantial protection 3

The difference between clinical trial efficacy (>90%) and real-world effectiveness (~70%) likely reflects differences in outcome specificity and the inclusion of more diverse patient populations in routine practice 3.

Protection Against Complications

• Postherpetic neuralgia (PHN): RZV demonstrates 88.8% efficacy in preventing PHN in adults ≥70 years 2, with real-world effectiveness of 76.0% 3
• HZ-related pain: The vaccine is effective against various HZ complications beyond PHN 4

Duration of Protection

• Protection persists for at least 8 years with minimal waning, maintaining efficacy above 83.3% during this period 1
• At 10 years, efficacy decreases to approximately 73%, which still represents meaningful protection 2
• No booster doses are currently recommended beyond the initial 2-dose series 1

Dosing Schedule Impact

• Two doses: 70.1% real-world effectiveness (95% CI, 68.6-71.5) 3
• Single dose: Only 56.9% effectiveness (95% CI, 55.0-58.8), demonstrating the critical importance of completing both doses 3
• Delayed second dose: Second doses administered beyond the recommended 2-6 month window (≥180 days) maintain full effectiveness without impairment 3

This finding is clinically important because patients who miss the recommended timing window should still complete the series rather than restart.

Special Populations

Immunocompromised Adults

• RZV is the first and only herpes zoster vaccine approved for immunocompromised adults aged ≥18 years 5, 4
• The vaccine demonstrates moderate to high efficacy with an acceptable safety profile in immunocompromised populations 5
• Effectiveness is maintained in patients with:
  • Autoimmune conditions (no significant reduction in 2-dose effectiveness) 3
  • Immunosuppressive conditions 3
  • Solid organ malignancies and hematologic malignancies 2
  • HIV/AIDS 2

Patients on Immunosuppressive Therapy

• Concomitant low-dose glucocorticoids (<10 mg/day prednisone equivalent) do not adversely impact vaccine response 1
• The vaccine maintains effectiveness even in patients on immunosuppressive therapy, though immune response may be somewhat reduced compared to healthy individuals 1

Comparison to Live-Attenuated Vaccine (Zostavax)

RZV offers dramatically superior efficacy compared to the older Zostavax (ZVL):

• Zostavax efficacy: 51% (range 46-70%) initially, declining to only 14.1% by year 10 6, 2
• Age-related decline with Zostavax: Efficacy drops from 70% in ages 50-59 to only 18% in those ≥80 years 1
• RZV maintains high efficacy across all age groups without significant age-related decline 1

Revaccination After Zostavax

• Adults who previously received Zostavax should receive the full 2-dose Shingrix series 1, 2
• Additional vaccination with RZV after prior ZVL lowered the incidence rate of HZ from 7.54 to 2.39 per 1000 person-years 6
• Pooled vaccine effectiveness against HZ was 75.5% (95% CI, 41.5%-89.7%) in adults aged ≥50 years who received ZVL within 5 years before RZV 6
• Minimum interval: At least 2 months (or 8 weeks) between ZVL and RZV 6, 1

Important Clinical Caveats

Why Vaccination Doesn't Prevent All Cases

• Even with 97% efficacy, approximately 3 out of 100 vaccinated people may still develop shingles 1
• Vaccine-induced immunity varies between individuals based on baseline immune function, age, and concurrent immunosuppressive conditions 1
• Cell-mediated immune responses correlate most strongly with protection 1
• However, vaccinated individuals who develop breakthrough shingles generally experience less severe disease and lower rates of PHN 1

Prior Shingles Does Not Eliminate Need for Vaccination

• Having shingles once does not provide reliable protection against future episodes 1
• The 10-year cumulative recurrence risk is 10.3% 6, 1
• Vaccination is recommended after a prior episode, waiting at least 2 months after acute symptoms resolve 6, 1

Safety Profile

• Common reactions: Injection-site pain, redness, and swelling occur frequently, with 9.5% experiencing grade 3 injection site reactions versus 0.4% with placebo 1
• Systemic symptoms: Myalgia, fatigue, and headache reported in 11.4% of vaccine recipients versus 2.4% in placebo recipients 1
• Serious adverse events: No increase compared to placebo groups in large clinical trials 1
• Autoimmune disease flares: Only mild flares (4-17%) after vaccination, with no serious adverse events 1