Monitoring pneumococcal carriage prevalence and serotype distribution is critical to better understand pneumococcal transmission dynamics and vaccine impact, particularly where routine disease surveillance is limited. This study aimed to describe and interpret heterogeneity in serotype-specific carriage globally before widespread use of pneumococcal conjugate vaccines (PCVs).
A systematic literature review was undertaken to identify all pneumococcal carriage observations across regions and age groups prior to PCV introduction. Bayesian nested meta-regression models were used for pooled estimates. The clustering of serotype distributions was assessed via hierarchical clustering.
In total 238 studies from 74 countries were included, comprising 493 age-specific data sets that contained 49,027 serotyped isolates. Serotypes 19F, 6B, 6A, 23F, and 14 were the five most prevalent in children <5 years. The proportion of PCV10 serotypes in carriage in <5y ranged from 45% (44% to 46%) in Asia to 59% (58% to 60%) in Europe, and that of PCV13 from 60% (59% to 61%) in Asia to 76% (75% to 77%) in Europe. The diversity of carried serotypes increased with age, however neither age, ethnicity, region or overall prevalence correlated well with the observed variations in serotype distribution across studies.
Globally, pneumococcal carriage was dominated by a few serotypes before the introduction of PCVs. Although variations in serotype distribution exist by geography and age, these are not easily attributable to a single discriminatory factor.
A systematic literature review was undertaken to identify all pneumococcal carriage observations across regions and age groups prior to PCV introduction. Bayesian nested meta-regression models were used for pooled estimates. The clustering of serotype distributions was assessed via hierarchical clustering.
In total 238 studies from 74 countries were included, comprising 493 age-specific data sets that contained 49,027 serotyped isolates. Serotypes 19F, 6B, 6A, 23F, and 14 were the five most prevalent in children <5 years. The proportion of PCV10 serotypes in carriage in <5y ranged from 45% (44% to 46%) in Asia to 59% (58% to 60%) in Europe, and that of PCV13 from 60% (59% to 61%) in Asia to 76% (75% to 77%) in Europe. The diversity of carried serotypes increased with age, however neither age, ethnicity, region or overall prevalence correlated well with the observed variations in serotype distribution across studies.
Globally, pneumococcal carriage was dominated by a few serotypes before the introduction of PCVs. Although variations in serotype distribution exist by geography and age, these are not easily attributable to a single discriminatory factor.