Effect of Pneumococcal Conjugate Vaccine on Nasopharyngeal Colonization among Immunized and Unimmunized Children in a Community‐Randomized Trial

Abstract

(See the article by Lipsitch et al., on pages 1221-7.)Background. Pneumococcal conjugate vaccines (PCVs) prevent vaccine serotype (VT) invasive disease; nonvaccine serotype (NVT) disease increases modestly. The impact of PCV on nasopharyngeal (NP) colonization is essential to understanding disease effects.Methods. We conducted a community-randomized controlled trial with catch-up vaccination through age 2 years investigating the effect of 7-valent PCV (PnCRM7) on NP colonization among American Indian infants and their unvaccinated contacts. Infants receiving blinded vaccine at 2, 4, 6, and 12-15 months of age had NP cultures obtained at age 7, 12, and 18 months. Serotype-specific colonization was detected by immunoblot.Results. We enrolled 566 vaccinated and 286 unvaccinated children from 511 households and collected 5157 specimens, of which 3525 (68.4%) had pneumococcus. PnCRM7 vaccinees were less likely to be colonized with VT (odds ratio [OR], 0.40 [95% confidence interval {CI}, 0.23-0.67]) but were more likely to be colonized with NVT pneumococci (OR, 1.67 [95% CI, 1.02-2.78]). PnCRM7 vaccinees were less densely colonized with VT strains than control vaccinees (OR, 0.61 [95% CI,). Day care-attending unvaccinated children in PnCRM7 communities were less likely to have VT colonization than those in control communities (OR, 0.27 [95% CI, 0.07-1.07]).Conclusions. PnCRM7 reduces the risk of VT acquisition and colonization density but increases the risk of NVT acquisition among vaccinees and their household contacts.

Reduced antibiotic prescribing for acute respiratory infections in adults and children

“…The decline in antibacterial use was faster for both older and younger children than for adults, although use in younger adults declined faster than for older adults. Possible reasons for these differences include: the influence of the pneumococcal conjugate vaccine on the perceived risk of child bacterial illness [43][44][45] and on parents' health through herd effects; 45,46 a potentially initially wider pool of unneeded antibacterial use in younger individuals; and a possible differential effect of demonstrated in this study, from 71% in 1990 to 59% in 2004, is similar to these US reports. Similarly, Steinman et al reported declining antibacterial use for child ARIs, from 41% in 1991 to 21% in 1999.…”

Carriage ofStreptococcus pneumoniae3 Years after Start of Vaccination Program, the Netherlands

“…Among parents of vaccinated children, carriage of PCV7 serotypes had almost disappeared. This impressive reduction of PCV7-serotype carriage in infants is larger than that observed in clinical trials, which showed 50%-60% reduction in PCV7 rates after conjugate vaccination, and should be attributed to herd effects (13,18,19). Herd effects would also account for the disappearance of PCV7 serotypes in parents.…”

Phenotypic and Genotypic Characterization of Streptococcus pneumoniae Strains Colonizing Children Attending Day-Care Centers in Norway

“…An immunoblot method designed to detect multiple serotypes in carriage studies was used in a study in Navajo and White Mountain Apache reservations. Multiple serotypes were detected in 8.1% of positive samples (6,34). In a study of pneumococcal carriage in the Gambia, serotyping was performed by latex agglutination, and multiple serotypes were identified in 11.5% of positive samples (30).…”