Table 3.

Impact of routine and catch-up herpes zoster vaccination on GP-diagnosed herpes zoster by time since cohorts were first eligible for vaccination

	Age on Sept 1, 2013, (age when first eligible for vaccination)	Average cumulative uptake*	Expected events†	Observed events	Incidence rate ratio (95% CI)‡	Expected incidence per 1000 person-years	Incidence reduction per 1000 person-years (95% CI)	Vaccine effectiveness (95% CI)§
Routine cohorts
First year after vaccine eligibility	68–70 years (70–71 years)	46%	354	255	0·72 (0·64–0·82)	8·7	2·4 (1·6–5·6)	62% (39–78)
Second year after vaccine eligibility	69–70 years (70–71 years)	65%	241	143	0·59 (0·50–0·70)	8·9	3·6 (2·7–4·5)	62% (54–77)
Third year after vaccine eligibility	70 years (70–71 years)	70%	117	65	0·56 (0·44–0·71)	9·2	4·1 (2·7–5·2)	64% (41–80)
All years of the programme	68–70 years (70–71 years)	56%	712	463	0·65 (0·60–0·72)	8·8	3·1 (2·5–3·5)	62% (50–71)
Catch-up cohorts
First year after vaccine eligibility	76–79 years (78–80 years)	46%	348	243	0·70 (0·62–0·79)	10·0	3·0 (2·1–3·8)	65% (46–83)
Second year after vaccine eligibility	77–79 years (78–80 years)	62%	251	151	0·60 (0·51–0·71)	10·2	4·0 (3·0–5·0)	64% (47–79)
Third year after vaccine eligibility	79 years (79–80 years)	60%	78	59	0·76 (0·59–0·98)	10·3	2·5 (0·2–4·2)	40% (3–68)
All years of the programme	76–79 years (78–80 years)	54%	677	453	0·67 (0·61–0·74)	10·1	3·1 (2·6–3·9)	62% (48–72)

Impact is shown by the incidence rate ratio (observed/expected events) and incidence reduction. GP=general practitioner.

^*Calculated by taking the mean of the cumulative uptake values in each month from October to September of the relevant years and cohorts.

^†Expected if the vaccine had not been introduced; based on model results for unvaccinated cohorts.

^‡Estimated from the Poisson regression model with a log-linear time trend, quadratic age effect, and the factor for vaccine eligibility.

^§Effectiveness required to generate the observed reductions in the first 3 years after vaccination.