What is the recommended dosing regimen for the shingles vaccine, specifically for adults aged 50 years and older?

Shingles Vaccine Dosing Regimen

The recommended dosing regimen for the shingles vaccine (Shingrix/RZV) in adults aged 50 years and older is two doses (0.5 mL each) administered intramuscularly, with the second dose given 2 to 6 months after the first dose. 1, 2, 3

Standard Dosing Schedule

• Administer the first dose at Month 0, followed by the second dose anytime between 2 and 6 months later 1, 2, 3
• The minimum interval between doses is 4 weeks; if the second dose is administered earlier than this minimum interval, the dose should be repeated 2
• If the second dose is administered beyond 6 months, effectiveness is not impaired—real-world data demonstrate that second doses given at ≥180 days maintain full effectiveness 2, 4
• The preferred injection site is the deltoid region of the upper arm 3

Special Population Modifications

Immunocompromised Adults (≥18 years)

• For immunocompromised patients, a shorter schedule is recommended with the second dose given 1 to 2 months after the first dose 2, 5
• This applies to patients with conditions including HIV infection, hematologic malignancies, solid organ transplant recipients, those on immunosuppressive therapy, and autoimmune diseases requiring immunosuppression 2

Hematopoietic Stem Cell Transplant Recipients

• For autologous HSCT recipients, administer RZV 50-70 days post-transplantation 2
• For allogeneic HSCT recipients, administer at least 6-12 months post-transplantation 5

Key Clinical Considerations

Vaccine Efficacy

• RZV demonstrates 97.2% efficacy in preventing herpes zoster in adults aged 50 years and older, with protection persisting for at least 8 years with minimal waning (maintaining efficacy above 83.3%) 2, 6
• Real-world effectiveness studies show 70.1% effectiveness for the two-dose series and 56.9% for a single dose, emphasizing the importance of completing both doses 4

Transitioning from Zostavax

• Adults who previously received the live-attenuated Zostavax (ZVL) should receive the full two-dose Shingrix series 2, 7
• Administer Shingrix at least 2 months after the last Zostavax dose 2, 7
• This recommendation is based on Zostavax's poor long-term protection, with efficacy declining to only 14.1% by year 10 2, 7

Vaccination After Acute Shingles Episode

• Administer Shingrix once acute symptoms have resolved, typically waiting at least 2 months after the episode 2, 5
• This waiting period allows for complete resolution of acute symptoms and immune system recovery 5
• Prior shingles history does not contraindicate vaccination, as the 10-year cumulative recurrence risk is 10.3% 2, 7

Expected Adverse Events

Local Reactions

• Pain at injection site occurs in 78.0% of recipients 1, 3
• Redness (38.1%) and swelling (25.9%) are common 1, 3
• Grade 3 injection site reactions (significant pain at rest preventing normal activities) occur in 9.5% versus 0.4% with placebo 2

Systemic Reactions

• Myalgia (44.7%), fatigue (44.5%), headache (37.7%), shivering (26.8%), fever (20.5%), and gastrointestinal symptoms (17.3%) are frequently reported 1, 3
• Systemic symptoms occur in 11.4% of vaccine recipients versus 2.4% in placebo recipients 2
• Most adverse events are mild to moderate in intensity and resolve within 4 days 2, 7

Serious Adverse Events

• No increased risk of serious adverse events or death compared to placebo 2, 6
• An increased risk of Guillain-Barré syndrome was observed during the 42 days following vaccination in postmarketing surveillance 3

Important Caveats

• Do not use the live-attenuated Zostavax in immunocompromised patients—only Shingrix (RZV) is appropriate for this population 2, 7, 5
• Shingrix is contraindicated in individuals with a history of severe allergic reaction (anaphylaxis) to any vaccine component or after a previous dose 3
• After reconstitution, administer immediately or store refrigerated between 2°C and 8°C (36°F and 46°F) and use within 6 hours 3
• Concerns about vaccine tolerability are the leading reason for both non-initiation and non-completion of the series, with individuals concerned about side effects being 1.22 times more likely to receive no doses and 1.83 times more likely to receive only one dose 8