Table 2.
Carriage prevalence and prevalence ratio for pneumococcal carriage among mothers, infants and children 1–15 years in Karonga District, Malawi, in the pre- and post-PCV13 periods.
| Vaccine status, 20141 | Carriage prevalence, 2009–2011 (pre PCV13 introduction) | Carriage prevalence, 2014 (post PCV13 introduction) | Crude prevalence ratio (95%CI) | Adjusted prevalence ratio (95%CI)3 | |
|---|---|---|---|---|---|
| All serotypes | |||||
| Infants, 6 wks | unvaccinated | 27/70 (38.6%) | 64/146 (43.8%) | 1.14 (0.80–1.61) | 0.98 (0.66–1.47) |
| Infants, 18 wks | fully vaccinated | 53/71 (74.7%) | 22/44 (50.0%) | 0.67 (0.48–0.93) | 0.60 (0.42–0.86)4 |
| Children 1–4 yrs2 | unvaccinated | 196/330 (59.4%) | 53/83 (63.9%) | 1.08 (0.89–1.29) | 1.06 (0.86–1.30)4 |
| fully vaccinated | – | 72/103 (70.0%) | 1.18 (1.01–1.37) | 1.08 (0.91–1.28)4 | |
| all | – | 141/207 (68.1%) | 1.15 (1.01–1.30) | 1.10 (0.97–1.25)4 | |
| Children 5–15 yrs | unvaccinated | 161/325 (49.5%) | 33/89 (37.1%) | 0.75 (0.56–1.00) | 0.73 (0.55–0.97)4 |
| HIV-negative mothers | unvaccinated | 100/595 (16.8%) | 64/418 (15.3%) | 0.92 (0.69–1.22) | 0.75 (0.47–1.17) |
| VT | |||||
| Infants, 6 wks | unvaccinated | 8/70 (11.4%) | 19/146 (13.0%) | 1.14 (0.52–2.47) | 1.07 (0.38–3.02) |
| Infants, 18 wks | fully vaccinated | 32/71 (45.1%) | 4/44 (9.1%) | 0.20 (0.08–0.53) | 0.24 (0.08–0.75)5 |
| Children 1–4 yrs2 | unvaccinated | 93/330 (28.2%) | 19/83 (22.9%) | 0.81 (0.53–1.25) | 0.84 (0.53–1.33)5 |
| fully vaccinated | – | 17/103 (16.5%) | 0.59 (0.37–0.93) | 0.54 (0.33–0.88)4 | |
| all | – | 37/207 (17.9%) | 0.63 (0.45–0.89) | 0.63 (0.45–0.90)4 | |
| Children 5–15 yrs | unvaccinated | 69/325 (21.2%) | 7/89 (7.9%) | 0.37 (0.18–0.78) | 0.37 (0.17–0.78) |
| HIV-negative mothers | unvaccinated | 39/595 (6.6%) | 10/418 (2.4%) | 0.37 (0.19–0.73) | 0.34 (0.15–0.79) |
| NVT | |||||
| Infants, 6 wks | unvaccinated | 19/70 (27.1%) | 45/146 (30.8%) | 1.14 (0.72–1.79) | 0.95 (0.57–1.56) |
| Infants, 18 wks | fully vaccinated | 21/71 (29.6%) | 18/44 (40.9%) | 1.38 (0.83–2.29) | 0.91 (0.47–1.77) |
| Children 1–4 yrs2 | unvaccinated | 103/330 (31.2%) | 34/83 (41.0%) | 1.31 (0.97–1.78) | 1.24 (0.88–1.74)4 |
| fully vaccinated | – | 55/103 (53.4%) | 1.71 (1.34–2.18) | 1.58 (1.21–2.06)4 | |
| all | – | 104/207 (50.2%) | 1.61 (1.30–1.99) | 1.50 (1.22–1.86) | |
| Children 5–15 yrs | unvaccinated | 92/325 (28.3%) | 26/89 (29.2%) | 1.03 (0.72–1.49) | 1.03 (0.71–1.49) |
| HIV-negative mothers | unvaccinated | 61/595 (10.3%) | 54/418 (12.9%) | 1.27 (0.90–1.79) | 0.99 (0.57–1.73) |
Fully vaccinated: 3 doses of PCV13; unvaccinated: no doses of PCV13 received; all: including partially vaccinated children and children with unknown vaccination status, in addition to the fully vaccinated and unvaccinated.
Children 1–4 years: carriage in 2014 of unvaccinated, fully vaccinated and all children 1–4 years is compared to carriage in 2009–2011 (pre-PCV13 period; all unvaccinated). Unvaccinated children 1–4 years in 2014: this includes samples from 9 children who were eligible for PCV13 in the catch-up cohort but received no vaccination, and 23 children who were not age-eligible for PCV13.
Adjusted for month of sample collection, number of children 1–4 years in the household, age, and within-person clustering (mother only). Using a generalized linear mixed model, there was negligible individual-level variance for children 1–4 years and 5–15 years of age (σ2 < 0.01), hence results from a (non-mixed) generalized linear model were reported. Using a generalized linear mixed model, the individual-level variance for mothers was 0.68 (all serotypes)/1.25 (PCV13)/1.03 (non-PCV13).
Log-binomial regression model data did not to converge so results of a Poisson model with robust standard errors are presented.