Volume 16, Number 5—May 2010
Research
Effects of Pneumococcal Conjugate Vaccine 2 Years after Its Introduction, the Netherlands
Table
Incidence rates of invasive pneumococcal diseases before and after implementation of 7-valent pneumococcal conjugate vaccine, the Netherlands*
Serotypes by patient age group, y | Preimplementation period (June 2004–June 2006) |
Postimplementation period (June 2006–June 2008) |
Preimplementation vs. postimplementation |
|||||
---|---|---|---|---|---|---|---|---|
No. cases | Rate | No. cases | Rate | IRR (95% CI) | p value† | |||
Total | ||||||||
All ages | 1,225 | 15.0 | 1,304 | 15.9 | 1.06 (0.98–1.15) | 0.14 | ||
<2 | 68 | 34.5 | 42 | 22.5 | 0.65 (0.44–0.96) | 0.006 | ||
2–4 | 25 | 8.1 | 26 | 8.7 | 1.07 (0.62–1.86) | |||
5–49 | 206 | 4.1 | 231 | 4.7 | 1.13 (0.94–1.37) | |||
50–64 | 254 | 16.7 | 292 | 18.5 | 1.11 (0.94–1.31) | |||
>65 |
672 |
58.8 |
713 |
60.2 |
1.02 (0.92–1.14) |
|||
Vaccine serotypes‡ | ||||||||
All ages | 570 | 7.0 | 561 | 6.9 | 0.98 (0.87–1.10) | |||
<2 | 48 | 24.3 | 15 | 8.0 | 0.33 (0.19–0.59) | <0.0001 | ||
2–4 | 17 | 5.5 | 17 | 5.7 | 1.03 (0.53–2.02) | |||
5–49 | 69 | 1.4 | 70 | 1.4 | 1.02 (0.73–1.43) | |||
50–64 | 114 | 7.5 | 129 | 8.24 | 1.09 (0.85–1.40) | |||
>65 |
322 |
28.2 |
330 |
27.9 |
0.99 (0.85–1.15) |
|||
Nonvaccine serotypes§ | ||||||||
All ages | 656 | 8.0 | 743 | 9.1 | 1.13 (1.02–1.26) | 0.02 | ||
<2 | 20 | 10.1 | 27 | 14.5 | 1.43 (0.80–2.55) | |||
2–4 | 8 | 2.6 | 9 | 3.0 | 1.16 (0.45–3.01) | |||
5–49 | 137 | 2.8 | 161 | 3.3 | 1.19 (0.94–1.49) | |||
50–64 | 140 | 9.2 | 163 | 10.3 | 1.12 (0.89–1.41) | |||
>65 | 350 | 30.6 | 383 | 32.4 | 1.06 (0.91–1.22) |
*Rate is cases/100,000 persons. IRR, incidence rate ratio; CI, confidence interval. Boldface indicates significant differences (p<0.05).
†p values shown <0.15; incidence rates pre vs. postimplementation period. Calculated by using Fisher exact test; all p values are 2 sided.
‡Streptococcus pneumoniae serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F.
§All other S. pneumoniae serotypes.