Table 3.
Number of cases and incidence of IPD in the baseline period and 2016–17 after vaccine introduction
| Baseline adjusted (crude) cases | Baseline adjusted (crude) incidence per 100 000 person-years | 2016–17 adjusted (crude) cases | 2016–17 adjusted (crude) incidence per 100 000 person-years | Crude IRR 2016–17 vs baseline (95% CI) | Adjusted IRR 2016–17 vs baseline (95% CI) | |
|---|---|---|---|---|---|---|
| Age 2–23 months | ||||||
| All | 62 (50) | 281 (226) | 20 (18) | 71 (63) | 0·28 (0·16–0·48) | 0·25 (0·15–0·42) |
| PCV7 | 29 (23) | 129 (104) | 2 (2) | 7 (7) | 0·07 (0·02–0·30) | 0·06 (0·01–0·23) |
| PCV13 | 47 (38) | 213 (171) | 6 (5) | 20 (17) | 0·10 (0·04–0·26) | 0·09 (0·04–0·24) |
| PCV13 only | 20 (16) | 89 (72) | 4 (3) | 12 (10) | 0·14 (0·04–0·51) | 0·14 (0·05–0·46) |
| Non-vaccine type | 15 (12) | 67 (54) | 15 (13) | 51 (45) | 0·83 (0·37–1·87) | 0·76 (0·37–1·61) |
| Age 2–4 years | ||||||
| All | 38 (33) | 118 (102) | 7 (6) | 16 (13) | 0·13 (0·04–0·31) | 0·13 (0·06–0·30) |
| PCV7 | 15 (13) | 46 (40) | 1 (1) | 2 (2) | 0·05 (0·001–0·37) | 0·05 (0·007–0·37) |
| PCV13 | 33 (29) | 103 (90) | 4 (3) | 8 (7) | 0·07 (0·01–0·24) | 0·08 (0·03–0·23) |
| PCV13 only | 19 (17) | 60 (53) | 3 (2) | 6 (4) | 0·08 (0·009–0·35) | 0·09 (0·02–0·34) |
| Non-vaccine type | 5 (4) | 15 (12) | 4 (3) | 8 (6) | 0·54 (0·08–3·16) | 0·54 (0·14–2·11) |
| Age 2–59 months | ||||||
| All | 100 (83) | 184 (153) | 28 (24) | 38 (32) | 0·21 (0·14–0·33) | 0·20 (0·13–0·31) |
| PCV7 | 43 (36) | 79 (66) | 3 (3) | 4 (4) | 0·06 (0·02–0·20) | 0·05 (0·02–0·17) |
| PCV13 | 80 (67) | 147 (123) | 9 (8) | 12 (11) | 0·09 (0·04–0·18) | 0·08 (0·04–0·17) |
| PCV13 only | 39 (33) | 72 (61) | 6 (5) | 8 (7) | 0·11 (0·04–0·29) | 0·11 (0·05–0·27) |
| Non-vaccine type | 20 (16) | 37 (29) | 18 (16) | 24 (22) | 0·74 (0·37–1·47) | 0·69 (0·36–1·29) |
| Age 5–14 years | ||||||
| All | 9 (10) | 10 (12) | 4 (3) | 3 (3) | 0·23 (0·05–0·98) | 0·31 (0·09–1·28) |
| PCV7 | 0 (0) | .. | 0 (0) | .. | .. | .. |
| PCV13 | 8 (9) | 9 (11) | 1 (1) | 1 (1) | 0·09 (0·008–0·87) | 0·11 (0·009–1·00) |
| PCV13 only | 8 (9) | 9 (11) | 1 (1) | 1 (1) | 0·09 (0·008–0·87) | 0·11 (0·009–1·00) |
| Non-vaccine type | 1 (1) | 1 (1) | 2 (2) | 2 (2) | 1·53 (0·10–22·9) | 1·53 (0·10–22·9) |
The baseline period was May 12, 2008 to May 11, 2010. Numbers of serotype-specific IPD cases may not sum to the number of all IPD cases due to five isolates that could not be serotyped. Case counts are adjusted for trends in patients eligible for investigation and rounded to the nearest integer. CIs calculated taking into account over-dispersed Poisson distributions in the 2–23 months and 5–14 years age groups. IPD=invasive pneumococcal disease. IRR=incidence rate ratio. PCV7=serotypes covered by PCV7: 4, 6B, 9V, 14, 18C, 19F, 23F, and cross-reactive 6A. PCV13=serotypes covered by PCV13. PCV13 only=serotypes covered by PCV13 but not PCV7: 1, 3, 5, 7F, and 19A. Non-vaccine type=serotypes not covered by PCV13.