Zostavax Dosing Recommendation
Zostavax is administered as a single 0.5 mL dose given subcutaneously for adults aged 50-79 years. 1
Standard Dosing
- One dose only of the live-attenuated vaccine containing a minimum of 1350 plaque-forming units (PFU) of Oka/Merck VZV 1
- Administered subcutaneously (not intramuscularly) 1, 2
- Approved for adults 50-79 years of age 1
- No booster dose is currently recommended or required 1
Important Clinical Context
Zostavax Has Been Largely Replaced
Zostavax is no longer the preferred herpes zoster vaccine and has been superseded by Shingrix (recombinant zoster vaccine). 3, 4 The Centers for Disease Control and Prevention now recommends Shingrix over Zostavax due to:
- Significantly superior efficacy: Shingrix demonstrates 97.2% efficacy versus Zostavax's 51.3% efficacy in preventing herpes zoster 3, 4
- Age-related efficacy decline with Zostavax: Efficacy drops from 70% (ages 50-59) to only 18% (ages ≥80) 3
- Waning protection: Zostavax efficacy decreases from 51.3% to 21.2% during years 7-11 post-vaccination 3
- Broader safety profile: Shingrix can be used in immunocompromised patients, while Zostavax is contraindicated 1, 3
Contraindications for Zostavax
Do not administer Zostavax to immunocompromised patients due to theoretical risk of serious disease from the live-attenuated virus, including: 1
- Primary or acquired immunodeficiency states 1
- Patients receiving immunosuppressive therapy 1
- Hematologic malignancies or solid tumors on active treatment 1
- HIV/AIDS patients 1
- Patients within 24 months of stem cell transplantation 1
Special Population: Post-Transplant Patients
For stem cell transplant recipients who might receive Zostavax (though RZV is now preferred):
- Wait at least 24 months post-transplant before administering the live vaccine 1
- One dose only of Zostavax is recommended at >24 months after ASCT 1
- Consider acyclovir prophylaxis as an alternative during the first 2 years 1
Transitioning from Zostavax to Shingrix
Patients who previously received Zostavax should receive the two-dose Shingrix series with no minimum interval required between the different vaccines. 3, 4 This recommendation exists because:
- Zostavax efficacy wanes to only 14.1% by year 10 4
- Shingrix provides superior and more durable protection 3, 4
Adverse Events Profile
Common injection site reactions with Zostavax include: 5, 2
- Erythema, swelling, and pain at injection site (most Grade 1-2 intensity) 5
- Grade 3 (severe) injection site reactions occur infrequently 5
- Generally well-tolerated with non-severe reactions 6, 2
- No difference in serious adverse events or deaths compared to placebo 7