Table 1. Incidence of invasive pneumococcal disease before and after implementation of a PCV7 vaccination program, the Netherlands, June 2004–May 2010*.
| Age group, y | Vaccination period† |
Late post- vs. pre-implementation period |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pre-implementation |
Early post- implementation |
Late
post-implementation |
||||||||||
| No. cases | Incidence | No. cases | Incidence | No. cases | Incidence | IRR | 95% CI | p value | ||||
| All serotypes | ||||||||||||
| All ages | 1,216 | 14.9 | 1,304 | 15.9 | 1,144 | 13.8 | 0.93 | 0.86–1.01 | NS | |||
| <2 | 68 | 35.0 | 42 | 22.8 | 26 | 14.1 | 0.40 | 0.26–0.63 | <0.001 | |||
| 2–4 | 25 | 8.2 | 26 | 8.9 | 12 | 4.3 | 0.52 | 0.26–1.04 | NS | |||
| 5–17 | 23 | 1.8 | 22 | 1.7 | 23 | 1.8 | 1.00 | 0.56–1.78 | NS | |||
| 18–49 | 181 | 4.9 | 209 | 5.8 | 197 | 5.5 | 1.11 | 0.91–1.36 | NS | |||
| 50–64 | 253 | 16.4 | 292 | 18.3 | 261 | 15.8 | 0.96 | 0.81–1.14 | NS | |||
|
>65 |
666 |
57.7 |
|
713 |
59.6 |
|
625 |
49.9 |
|
0.87 |
0.78–0.97 |
0.009
|
| PCV7 serotypes | ||||||||||||
| All ages | 565 | 6.9 | 561 | 6.9 | 268 | 3.2 | 0.47 | 0.40–0.54 | <0.001 | |||
| <2 | 48 | 24.7 | 15 | 8.1 | 0 | 0.0 | 0 | NA | <0.001 | |||
| 2–4 | 17 | 5.6 | 17 | 5.8 | 3 | 1.1 | 0.19 | 0.06–0.66 | 0.003 | |||
| 5–17 | 11 | 0.9 | 4 | 0.3 | 4 | 0.3 | 0.36 | 0.12–1.14 | NS | |||
| 18–49 | 56 | 1.5 | 66 | 1.8 | 48 | 1.3 | 0.87 | 0.59–1.29 | NS | |||
| 50–64 | 114 | 7.4 | 129 | 8.1 | 56 | 3.4 | 0.46 | 0.33–0.63 | <0.001 | |||
|
>65 |
319 |
27.6 |
|
330 |
27.6 |
|
157 |
12.5 |
|
0.45 |
0.37–0.55 |
<0.001
|
| Non–PCV7 serotypes | ||||||||||||
| All ages | 650 | 8.0 | 741 | 9.1 | 876 | 10.6 | 1.33 | 1.20–1.47 | <0.001 | |||
| <2 | 20 | 10.3 | 27 | 14.7 | 26 | 14.1 | 1.37 | 0.77–2.46 | NS | |||
| 2–4 | 8 | 2.6 | 9 | 3.1 | 9 | 3.2 | 1.22 | 0.47–3.18 | NS | |||
| 5–17 | 12 | 0.9 | 18 | 1.4 | 19 | 1.5 | 1.58 | 0.77–3.26 | NS | |||
| 18–49 | 125 | 3.4 | 142 | 3.9 | 149 | 4.1 | 1.22 | 0.96–1.54 | NS | |||
| 50–64 | 139 | 9.0 | 163 | 10.2 | 205 | 12.4 | 1.37 | 1.11–1.70 | 0.004 | |||
| >65 | 346 | 30.0 | 382 | 32.0 | 468 | 37.4 | 1.25 | 1.09–1.43 | 0.002 | |||
*Cases are number of patients included in a study covering ≈25% of the Dutch population; incidence is number of cases/100,000 persons. Three pneumococcal isolates (1 in the pre- and 2 in the early post-implementation period) were either not typeable or typed as a rough strain and, therefore, could not be classified as 7-valent pneumococcal conjugate vaccine (PCV7) or non–PCV7 serotypes. IRR, incidence rate ratio; NS, not significant (p>0.05); NA, not applicable; boldface, significant difference (p<0.05). †Vaccination periods: pre-implementation period, June 2004–May 2006; early post-implementation, June 2006–May 2008; late post-implementation period, June 2008–May 2010.