Pneumococcal Carriage in Burkina Faso After 13-Valent Pneumococcal Conjugate Vaccine Introduction and Before a Schedule Change

Abstract

Background. In October 2013, Burkina Faso introduced 13-valent pneumococcal conjugate vaccine (PCV13) into the routine childhood immunization program using 3 primary doses with no booster. Previous pneumococcal carriage studies showed reductions in vaccine-type (VT) carriage in children aged <5 years but not in older age groups. Methods. We conducted a cross-sectional, age-stratified pneumococcal carriage study among healthy persons aged ≥1 month in Bobo-Dioulasso in March 2020. Pneumococci isolated by culture from nasopharyngeal swabs (all participants) and oropharyngeal swabs (participants aged ≥5 years) were serotyped by polymerase chain reaction; a subset was serotyped by Quellung. Using data from a study with the same design from March 2017, we examined changes in pneumococcal carriage by age group. Results. Among 1005 (2017) and 1002 (2020) enrolled participants, VT carriage decreased (21.6% to 15.9%; adjusted prevalence ratio [aPR], 0.76 [95% confidence interval {CI}, .63–.92]). By age group, decline in VT carriage was significant among children aged 5–14 years (28.9% to 16.3%; aPR, 0.57 [95% CI, .39–.84]) but not among children aged <5 years (22.4% to 19.1%; aPR, 0.87 [95% CI, .70–1.09]) or adults aged ≥15 years (12.0% to 5.5%; aPR, 0.52 [95% CI, .26–1.05]). Conclusions. Between 3 and 6 years after PCV13 introduction, significant declines in VT carriage were observed in older children, possibly reflecting indirect effects of PCV13 use. VT carriage in children aged <5 years remained stable with almost 1 in 5 carrying VT pneumococci, suggesting limitations to a PCV schedule without a booster dose.