Pneumococcal Carriage in Burkina Faso After 13-Valent Pneumococcal Conjugate Vaccine Introduction: Results From 2 Cross-sectional Population-Based Surveys

Abstract

Background Burkina Faso, a country in Africa’s meningitis belt, introduced 13-valent pneumococcal conjugate vaccine (PCV13) in October 2013, with 3 primary doses given at 8, 12 and 16 weeks of age. To assess whether the new PCV13 program controlled pneumococcal carriage, we evaluated overall and serotype-specific colonization among children and adults during the first 3 years after introduction. Methods We conducted 2 population-based, cross-sectional, age-stratified surveys in 2015 and 2017 in the city of Bobo-Dioulasso. We used standardized questionnaires to collect sociodemographic, epidemiologic, and vaccination data. Consenting eligible participants provided nasopharyngeal (all ages) and oropharyngeal (≥5 years only) swab specimens. Swab specimens were plated onto blood agar either directly (2015) or after broth enrichment (2017). Pneumococci were serotyped by conventional multiplex polymerase chain reaction. We assessed vaccine effect by comparing the proportion of vaccine-type (VT) carriage among colonized individuals from a published baseline survey (2008) with each post-PCV survey. Results We recruited 992 (2015) and 1005 (2017) participants. Among children aged <5 years, 42.8% (2015) and 74.0% (2017) received ≥2 PCV13 doses. Among pneumococcal carriers aged <1 year, VT carriage declined from 55.8% in 2008 to 36.9% in 2017 (difference, 18.9%; 95% confidence interval, 1.9%–35.9%; P = .03); among carriers aged 1–4 years, VT carriage declined from 55.3% to 31.8% (difference, 23.5%; 6.8%–40.2%; P = .004); and among participants aged ≥5 years, no significant change was observed. Conclusion Within 3 years of PCV13 implementation in Burkina Faso, we documented substantial reductions in the percentage of pneumococcal carriers with a VT among children aged <5 years, but not among persons aged ≥5 years. More time, a change in the PCV13 schedule, or both, may be needed to better control pneumococcal carriage in this setting.

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

“…A previous report comparing carriage studies conducted in Bobo-Dioulasso in 2015 (1 year post–PCV13 introduction) and 2017 (3 years post-PCV13 introduction, also included in the current study) showed reductions in VT carriage among pneumococcal carriers aged <5 years, although there were differences in the laboratory methods used for pneumococcal detection between the studies conducted in 2015 and 2017 [ 11 ]. Between 2017 and 2020, we observed no further significant reduction in VT carriage among children aged <5 years.…”

“…In March 2020, we conducted a cross-sectional, age-stratified community pneumococcal carriage study in Bobo-Dioulasso, a city located in Western Burkina Faso. We used the same recruiting methods as previous pneumococcal carriage studies conducted in Bobo-Dioulasso pre- and post-PCV13 introduction (2008, 2015, 2017) [ 11 , 16 ] and compared with data from the 2017 survey. Target sample size for each study (2017 and 2020) was 1000 persons aged ≥1 month with 200 participants each in 5 age groups: 1–11 months, 1 year, 2–4 years, 5–14 years, and ≥15 years.…”

“…Data collection methods have been previously described [ 11 ]. In brief, surveyors collected information on household characteristics and demographics from all consenting participants.…”

“…Crude prevalence ratios (PRs) were calculated using standard methods with 2017 serving as the reference period. We reviewed literature to identify potential confounders associated with pneumococcal carriage (inside cooking location, presence of other children aged <5 years in the household, antibiotic use in the past 2 weeks, and illness in the past 2 weeks) for a priori inclusion in the adjusted model [ 11 , 19–22 ]. We also looked at participant characteristics that changed from 2017 and 2020 ( Table 1 ) and whether there were any significant differences in pneumococcal carriage prevalence by those characteristics ( Supplementary Table 1 ) to inform our model selection.…”

“…Pre- (2008) and post-PCV13 introduction (2015, 2017) pneumococcal carriage studies conducted in Bobo-Dioulasso, Burkina Faso showed reductions in VTs among pneumococcal carriers aged <5 years, but not among participants ≥5 years [ 11 ]. Approximately 3 years post-PCV13 introduction (2017 study), VT carriage remained high among children aged <5 years (22%), older children aged 5–14 years (29%), and adults aged ≥15 years (12%) [ 11 ] compared to middle- and high-income countries using PCVs (children <5 years: 1.4%–11.2%; adults: 0.0%–9.0%) [ 12–15 ]. Nationwide bacterial meningitis surveillance showed declines in VT pneumococcal meningitis 4 years after vaccine introduction; however, serotype 1, included in PCV13, remained the predominant serotype causing pneumococcal meningitis among all ages [ 9 ].…”