Incidence of non-invasive all-cause pneumonia in children in the United States before and after the introduction of pneumococcal conjugate vaccines: a retrospective claims database analysis

Table 4 Estimated changes in ACP IRs at the end of each PCV study period vs. prior period and pre-PCV7 period among commercially insured children aged 0–17 years (1998–2018)

Period	IRR (95% CI)
Period	All ages	Ages < 2 years	Ages 2–4 years	Ages 5–17 years
End of Early PCV7 vs. End of Pre-PCV7	0.90 (0.50, 1.62)	0.48 (0.26, 0.90)	0.56 (0.30, 1.02)	1.28 (0.60, 2.72)
End of Late PCV7 vs. End of Early PCV7	1.34 (1.14, 1.55)	1.10 (0.95, 1.27)	1.10 (0.95, 1.28)	1.58 (1.30, 1.92)
End of Late PCV7 vs. End of Pre-PCV7	1.20 (0.67, 2.19)	0.53 (0.28, 0.99)	0.61 (0.33, 1.13)	2.02 (0.95, 4.36)
End of Early PCV13 vs. End of Late PCV7	0.65 (0.56, 0.76)	0.75 (0.65, 0.87)	0.80 (0.69, 0.92)	0.58 (0.48, 0.71)
End of Late PCV7 vs. End of Pre-PCV7	0.78 (0.43, 1.43)	0.40 (0.21, 0.75)	0.49 (0.26, 0.91)	1.18 (0.55, 2.57)
End of Late PCV13 vs. End of Early PCV13	1.51 (1.12, 2.04)	1.19 (0.91, 1.57)	1.31 (1.00, 1.75)	1.68 (1.14, 2.46)
End of Late PCV13 vs. End of Pre-PCV7	1.18 (0.61, 2.31)	0.48 (0.24, 0.94)	0.64 (0.32, 1.26)	1.98 (0.86, 4.70)

[1] Results were calculated using coefficients from a generalized linear model with negative binomial distribution and log link, controlling for seasonality using month indicators
[2] Time periods were defined as follows: Pre-PCV7: 1998–1999; Early PCV7: 2001–2005; Late PCV7: 2006–2009; Early PCV13: 2011–2013; Late PCV13: 2014–2018. Years 2000 and 2010 were considered transition years and were excluded from the model
[3] 95% confidence intervals were obtained by bootstrapping the model coefficients using 10,000 replications
Abbreviations: ACP All-cause pneumonia, CI Confidence interval, IR Incidence rate, IRR Incidence rate ratio, PCV Pneumococcal conjugate vaccine

ISSN: 2200-6133