Effect of Reduced-Dose Schedules With 7-Valent Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Carriage in Children

Abstract

HE SUCCESS OF THE INTRODUCtion in 2000 in the United States of routine infant vaccination with the licensed 7-valent pneumococcal conjugate vaccine (PCV-7) is based on direct protection against vaccine serotype pneumococcal disease among vaccinees but also on the observed and unexpectedly large and widespread reduction in invasive and respiratory (eg, pneumonia and otitis media) vaccine serotype pneumococcal disease in nonimmunized individuals (indirect effect or herd protection). 1-6 This herd effect has been attributed to reduced carriage of vaccine serotype pneumococci in vaccinated infants and subsequent transmission to (household) adult contacts and spread in the community. The resulting decreased circulation of the 7 serotypes and herd effects have contributed substantially to the public health benefit and costeffectiveness of PCV-7 programs. 7,8 Increasingly crowded infant vaccine schedules and less favorable cost

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

“…Second, the postvaccination data came from a cross-sectional cohort study including 2 separate age groups, whereas the pre-PCV7 control data were derived from a longitudinal study in which data were collected from the same children at age 12 and 24 months. However, we previously found that potential within-person dependency was not substantially affecting these carriage data, probably because of the large interval between carriage sample collections (13). Third, the study was not adequately powered to evaluate serotype-specifi c differences.…”

“…Transoral swabs of the directly observed posterior pharynx were collected on a rigid cotton-wool swab. All swabs in both studies were processed according to the same study procedures by the same laboratory for microbiology as described (13). Briefl y, swabs were cultured for S. pneumoniae, then 1 pneumococcal colony per plate was subcultured and serotyped by the capsular swelling method (Quellung reaction).…”

“…Data on S. pneumoniae carriage were compared with data from the pre-PCV7 control cohort at age 12 months (n = 319) and 24 months (n = 321) and the parents of the 24-month-old children (n = 296) in which children were enrolled as described previously (13). According to protocol, the primary study outcome was defi ned as the prevalence of any of the PCV7 serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F) and any of the non-PCV7 serotypes (all other pneumococcus serotypes including nontypeable isolates) in children.…”

Significant decline in pneumonia admission rate after the introduction of routine 2+1 dose schedule heptavalent pneumococcal conjugate vaccine (PCV7) in children under 5 years of age in Kielce, Poland

“…However, the Municipal Council in Kielce decided to apply the 2+1 scheme, as it was not only cheaper, which was a particularly important factor in this case, but also, as evidenced in numerous studies [13,15,16,28], was as efficient in a mass vaccination pattern as the original 3+1 scheme. The scheme was, thus, approved for population vaccination also in the registration dossier.…”

Update on the Use of Conjugate Pneumococcal Vaccines in Childhood

“…Children and their parents were tested for NP carriage of S. pneumoniae at 12 months, 18 months and 24 months of age. In the two vaccinated groups, fewer children and their parents were colonized with S. pneumoniae (24) compared to controls suggesting that herd immunity can be maintained with two or three doses of PNEU-C-7. (25) Within the European Union, in 2009, 11 of 24 countries reporting PNEU-C-7 programs used a three-dose schedule for all children, and a twelfth (Switzerland) recommended a three-dose schedule for healthy children but a four-dose schedule for children with chronic conditions increasing their risk of IPD.…”