Shingrix Protocol for Incomplete Series in Canada
Complete the Shingrix series by administering the second dose now, regardless of how many years have elapsed since the first dose. 1
Standard Completion Protocol
The patient should receive the second dose of Shingrix immediately, with no need to restart the series. 1 Canadian guidelines align with international recommendations that there is no maximum interval between doses—the series does not need to be restarted regardless of the time elapsed since the first dose 1, 2.
Key Implementation Points
Administer the second dose at the next available clinical encounter without delay, as waiting serves no purpose while leaving the patient vulnerable to herpes zoster 1
No minimum interval restriction applies when years have passed since the first dose—the patient can receive the second dose immediately 1
Do not restart the series even if many years have elapsed; one dose provides partial protection (approximately 57% effectiveness), but completing the series increases effectiveness to approximately 70% 3
Evidence Supporting Delayed Second Dose
The evidence strongly supports completing interrupted series:
Real-world data demonstrates that second doses administered beyond the recommended 2-6 month window maintain full effectiveness, with no impairment when given at ≥180 days after the first dose 3
A large Medicare cohort study found vaccine effectiveness of 70.1% for two doses versus 56.9% for a single dose, confirming the substantial benefit of series completion 3
Protection persists for at least 8 years after completing the two-dose series, with efficacy maintained above 83% during this period 1
Clinical Rationale
The recombinant zoster vaccine (Shingrix) is strongly preferred over the older live-attenuated vaccine (Zostavax) for all adults aged ≥50 years, including those who previously received partial vaccination 1, 2. Shingrix demonstrates:
Superior efficacy of >90% across all age groups ≥50 years, compared to Zostavax which showed only 14.1% efficacy by year 10 1
High efficacy of 97.2% in preventing herpes zoster in adults aged 50 years and older in pivotal trials 1
Effectiveness against postherpetic neuralgia of 76% in real-world studies 3
Important Caveats
The patient may experience injection-site reactions (pain, redness, swelling) and systemic symptoms (fatigue, myalgia), which occur in approximately 9.5% and 11.4% of recipients respectively, but these are typically mild to moderate and transient 1
No serious safety concerns have been identified in large clinical trials, with similar rates of serious adverse events between vaccine and placebo groups 1
Document completion of the series to ensure the patient receives full protection and does not inadvertently receive additional unnecessary doses 1