Dose 1 — Priming the Immune System
The first injection introduces the response.
- Recombinant: Vaccine type (gE antigen + AS01B adjuvant)
- IM: Route (deltoid muscle)
- 0%: Baseline titer (pre-vaccination)
- AS01B: Adjuvant (liposome-based)
What happens at dose 1
Placeholder: dose 1 introduces antigen and adjuvant to trigger priming.
Initial Immune Response Building
Titers rise over the first weeks after dose 1.
- ~Week 4: Peak (dose 1) (partial response)
- CD4+ T-cell: Response type (plus antibody titer)
- Partial: Protection level (single-dose only)
- ~Month 2: Decline onset (without dose 2)
Why response builds gradually
Placeholder: response builds gradually as immune cells expand and differentiate.
Dose 2 Timing Window — 2 to 6 Months
Giving dose 2 within this window is critical for efficacy.
- Month 2: Window opens (earliest allowed)
- Month 6: Window closes (label guidance)
- Still valid: Late dosing (no need to restart series)
- Lower boost: Missed window risk (reduced anamnestic peak)
Why timing matters
Placeholder: the window balances priming maturity against waning response.
Dose 2 Boost Response
The second dose drives a much sharper titer spike.
- ~3–4×: Boost magnitude (vs. dose 1 peak)
- ~4 weeks post-dose 2: Peak timing (anamnestic response)
- ~97%: Zoster efficacy (immunocompetent adults)
- ~91%: PHN efficacy (immunocompetent adults)
Anamnestic boosting mechanism
Placeholder: memory cells from dose 1 drive a faster, larger second response.
Sustained Protection and Immune Status Impact
Long-term titers and efficacy differ by immune status.
- ~10 years: Duration studied (follow-up data)
- ~90%+: Immunocompetent efficacy (through year 4)
- ~68–87%: Immunocompromised efficacy (varies by condition)
- Slow: Titer decline rate (gradual waning)
Immune status effect on durability
Placeholder: immunocompromised patients show a lower, faster-waning titer curve.
Placeholder: monitoring and possible revaccination guidance may apply.