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. Author manuscript; available in PMC: 2022 Nov 14.
Published in final edited form as: Vaccine. 2021 Sep 4;39(41):6144–6150. doi: 10.1016/j.vaccine.2021.08.070

Table 3:

Piecewise constant 1- incidence rate ratio (1-IRR) estimates with 95% confidence intervals (CI) for 5 doses of aP vaccine among 5–9 year old children living in King County, WA, between January 1, 2013, and December 31, 2017

Time since vaccination (years) Cases in vaccinated group Person-time at risk in vaccinated group Cases in under-vaccinated group Person-time at risk in under-vaccinated group VEIR(t) 95% CI
1 4 1,213,657 8 259,261 0.91 0.70, 0.97
2 10 937,463 12 206,559 0.82 0.58, 0.92
3 3 678,022 4 156,973 0.81 0.19, 0.96
4 2 421,552 7 102,776 0.93 0.67, 0.98
5 3 165,978 2 41,096 0.64 −1.14, 0.94

VEIR(t): Vaccine effectiveness at time t

Poisson regression models are adjusted for age and neighborhood SES index.

Person time at risk measured in months