Why is the shingles (varicella-zoster) vaccine recommended for individuals aged 50 or over?

Why Shingles Vaccine is Recommended for Age 50 and Over

The shingles vaccine is recommended starting at age 50 because herpes zoster incidence rises sharply at this age threshold, and the recombinant zoster vaccine (Shingrix) demonstrates >90% efficacy in preventing shingles and its complications in all adults aged 50 and older, with sustained protection for at least 8 years. 1

Epidemiologic Rationale for Age 50 Threshold

The age-specific incidence of herpes zoster increases substantially starting around age 50-60 years, marking a critical inflection point in disease risk 2. This sharp rise correlates directly with age-related decline in varicella-zoster virus (VZV)-specific cell-mediated immunity 2, 3.

• The lifetime risk of developing shingles is approximately 25-33%, with the majority of cases occurring after age 50 2, 4
• Before age 45, only 8.6% of males and 10.5% of females have experienced shingles, but the risk over an expected lifetime for those aged 45 years is 22% for males and 32% for females 5
• The risk for postherpetic neuralgia (PHN)—the most debilitating complication—is 10-18% in patients with zoster, and this complication disproportionately affects older adults 4

Vaccine Efficacy Evidence Supporting Age 50

The pivotal ZOE-50 trial established Shingrix's 97.2% vaccine efficacy specifically in adults aged 50 years and older, providing the evidence base for FDA approval at this age threshold. 1, 6

• Efficacy remains >90% across all age groups 50 and older, including those aged 70+ years (89.8% efficacy) 7
• Protection persists above 83.3% for at least 8 years with minimal waning 1
• The vaccine demonstrates 88.8% efficacy against postherpetic neuralgia in adults ≥70 years 7

This represents a dramatic improvement over the older live-attenuated vaccine (Zostavax), which showed only 51% initial efficacy and declined to just 14.1% by year 10 1, 2

Regulatory and Guideline Consensus

Multiple authoritative bodies converge on age 50 as the standard threshold:

• The CDC Advisory Committee on Immunization Practices (ACIP) recommends Shingrix for all immunocompetent adults aged ≥50 years 1, 7
• The American College of Physicians, American Geriatrics Society, and international guidelines from Taiwan, Canada, and the United Kingdom consistently recommend vaccination starting at age 50 1, 7
• The FDA approved Shingrix for adults aged ≥50 years based on the ZOE-50 trial data 7

Ophthalmologists and other specialists should strongly recommend that patients 50 years and older obtain vaccination with recombinant zoster vaccine (Shingrix), working collaboratively with primary care to ensure vaccination starting at age 50. 8

Why Not Earlier for Immunocompetent Adults?

The age 50 threshold reflects a balance between disease burden and vaccine trial evidence:

• Herpes zoster incidence is relatively low in immunocompetent individuals under age 50 compared to older adults 7
• The pivotal efficacy trials enrolled adults aged ≥50 years, not younger populations, so efficacy data below age 50 in immunocompetent individuals does not exist 7
• International guidelines provide strong recommendations (Grade 1B) for vaccination in immunocompetent adults aged ≥50 years, with no provisions for younger immunocompetent adults 6

Important Exception: Immunocompromised Patients Under Age 50

The only scenario where vaccination before age 50 is recommended is for immunocompromised adults aged ≥18 years, including those with hematologic malignancies, solid organ transplant recipients, HIV infection, autoimmune diseases requiring immunosuppressive therapy, or chronic high-dose glucocorticoids (≥20 mg/day prednisone equivalent). 7

• These patients face substantially elevated herpes zoster risk regardless of age 7
• Shingrix is the only appropriate vaccine for immunocompromised individuals, as the live-attenuated Zostavax is absolutely contraindicated 8, 7
• A shortened vaccination schedule (second dose at 1-2 months rather than 2-6 months) is recommended for immunocompromised adults 7

Clinical Implementation Algorithm

For patients aged 50 and older:

• Administer Shingrix as a 2-dose series with the second dose given 2-6 months after the first dose 1
• Vaccinate regardless of prior shingles history (wait at least 2 months after acute symptoms resolve) 1, 6
• Vaccinate even if previously received Zostavax (wait at least 2 months after Zostavax) 1
• No serologic testing or varicella history is required before vaccination 4

Common Pitfalls to Avoid

• Do not confuse varicella (chickenpox) vaccination with herpes zoster vaccination—if a patient is VZV-seronegative (never had chickenpox), they need varicella vaccine, not shingles vaccine 7
• Never use live-attenuated Zostavax in immunocompromised patients—only Shingrix is appropriate for this population 8, 7
• Do not delay vaccination in patients aged 50+ who previously received Zostavax—they should receive the full 2-dose Shingrix series due to Zostavax's inadequate long-term protection 1
• Do not assume prior shingles provides adequate protection—the 10-year cumulative recurrence risk is 10.3%, and vaccination is recommended after a prior episode 1