I received one dose of a zoster vaccine on [date]; do I need a second dose?

Yes, You Need a Second Dose of Shingrix

If you received only one dose of a zoster vaccine, you must complete the two-dose Shingrix series for optimal protection against shingles. The single dose you received provides inadequate protection compared to the full two-dose regimen.

Understanding Your Vaccination Status

The critical question is which vaccine you received:

• If you received Zostavax (the older live vaccine): You need the complete 2-dose Shingrix series, administered at least 2 months after your Zostavax dose 1, 2.

• If you received one dose of Shingrix: You need to complete the series with a second dose 1, 2.

Why the Second Dose Matters

The two-dose Shingrix regimen demonstrates 97.2% efficacy in preventing shingles, compared to only 56.9% efficacy with a single dose 3. Real-world data from Medicare beneficiaries shows that completing the two-dose series provides 70.1% effectiveness, while a single dose achieves only 56.9% effectiveness 3. This represents a substantial difference in protection that directly impacts your risk of developing shingles and postherpetic neuralgia.

Protection Duration and Waning

• Shingrix maintains efficacy above 83.3% for at least 8 years with minimal waning when both doses are completed 2.
• In contrast, the older Zostavax vaccine shows dramatic efficacy decline to only 14.1% by year 10 2, 4.

Recommended Dosing Schedule

For immunocompetent adults aged ≥50 years:

• Second dose should be given 2-6 months after the first dose 1, 2.
• The minimum acceptable interval is 4 weeks; if given earlier, the dose must be repeated 1, 2.
• If the second dose is delayed beyond 6 months, effectiveness is not impaired—you should still complete the series 3.

For immunocompromised adults aged ≥18 years:

• A shorter schedule with the second dose at 1-2 months after the first is recommended 2, 5.

Real-World Completion Rates

Among people who received a first dose of Shingrix between October 2017 and September 2019, approximately 70% completed the two-dose series within 6 months and 80% within 12 months 6. Do not become part of the 20-30% who fail to complete the series and remain inadequately protected.

Common Pitfalls to Avoid

• Never assume one dose is sufficient based on side effects or perceived immunity 2, 3.
• Do not confuse the interval between doses with the waiting period after a shingles episode (which is ≥2 months after symptom resolution) 2, 5.
• Do not delay the second dose indefinitely—while late completion still provides protection, completing within the recommended timeframe ensures optimal immune response 3.
• If you previously received Zostavax, do not skip Shingrix thinking you're already protected—Zostavax provides inadequate long-term protection 2, 4.

Practical Next Steps

1. Identify which vaccine you received by checking your vaccination record or contacting the administering provider 1.
2. Schedule your second Shingrix dose immediately if you received one dose of Shingrix, regardless of how long ago 3.
3. If you received Zostavax, schedule the first dose of Shingrix at least 2 months after your Zostavax dose, followed by the second Shingrix dose 2-6 months later 1, 2.