Is it acceptable to administer the second dose of the herpes zoster (shingles) vaccine more than 3 months after the initial dose?

From the Guidelines

It is acceptable to administer the second dose of the herpes zoster (shingles) vaccine more than 3 months after the initial dose, with the recommended interval being 2-6 months apart 1. The recombinant zoster vaccine (RZV) is given in 2 doses, and the timing of the second dose can be flexible, with some guidelines suggesting that it can be given 1-2 months after the first dose for adults at increased risk 1. Key points to consider when administering the second dose of the shingles vaccine include:

• The recommended interval between the two doses is 2-6 months apart 1
• If more time has elapsed, the second dose should still be given as soon as possible without restarting the series
• The Centers for Disease Control and Prevention (CDC) advises that if the second dose is given later than the recommended timeframe, there's no need to restart the vaccination series
• The second dose is crucial for achieving the full protection that the vaccine offers, which is more than 90% effective at preventing shingles 1
• Even if it's been significantly longer than 6 months since the first dose, getting that second dose will still provide the intended protection against shingles and its complications. In clinical practice, the goal is to provide the best possible protection against shingles and its complications, and administering the second dose of the vaccine, even if it's more than 3 months after the initial dose, is a crucial step in achieving this goal 1.

From the Research

Administration of the Second Dose of Herpes Zoster Vaccine

• The recommended schedule for the recombinant zoster vaccine (RZV) is two doses, two months apart 2.
• However, studies have shown that administering the second dose more than 3 months after the initial dose does not impair effectiveness 3.
• In fact, one study found that the 2-dose vaccine effectiveness was not significantly lower for beneficiaries who received their second dose at ≥180 days 3.
• Another study reported that 70% and 80% of participants completed the two-dose series within six and 12 months post initial dose, respectively 4.
• The Centers for Disease Control and Prevention (CDC) and the Advisory Committee on Immunization Practices (ACIP) recommend that the second dose of RZV be administered 2-6 months after the first dose 2.

Vaccine Effectiveness and Safety

• Studies have consistently shown that the RZV is effective in preventing herpes zoster and postherpetic neuralgia in adults aged ≥50 years 3, 5, 2.
• The vaccine has a favorable safety and tolerability profile, with the most commonly reported adverse events being non-severe injection-site reactions 5, 6.
• The risk of serious adverse events and deaths is not significantly higher in vaccinated individuals compared to those who received a placebo 5.