OBJECTIVE: The 13-valent and 10-valent pneumococcal conjugate vaccines (PCV13 and PCV10, respectively) did not meet the prespecified efficacy threshold for certain 7-valent (PCV7) serotypes in their immunogenicity trials. This study estimates the real-world population-level impact of pneumococcal conjugate vaccine (PCV) infant national immunization programs (NIPs) on burden of disease due to serotypes for which the PCV missed its primary endpoint in immunogenicity trials (6B and 9V for PCV13; 6B and 23F for PCV10).
METHODS: We identified countries (Canada, Germany, Israel, Italy, South Africa, and the United States) with national IPD surveillance data that introduced the seven-valent PCV (PCV7) followed by PCV13, as well as countries that introduced PCV7 and PCV10 (Finland, Brasil, the Netherlands). We extracted IPD cases by serotype group [6B+9V; PCV7 serotypes minus 6B and 9V/23F] and by age group (<5 years, 5-64 years, and ≥65 years). For each country, we calculated the annual case counts for eight years following PCV13/PCV10 introduction and compared these counts to the counts from the year prior to initiating PCV13/PCV10.
RESULTS: Cases due to serotypes 6B and 9V generally decreased over time following introduction of PCV13 across countries. For ages <5 years, an approximate steady state after 5 years was reached with roughly 85% to 100% decrease in cases. For ages 5-64 years, case counts dropped approximately 17-90%, while for ages 65+ the decrease ranged from 33% to 86%. Incidence declines were similar for the remaining PCV7 serotypes in each country other than Canada and Italy, which observed increases in PCV7 in ages>=5. Decreases ranges from 43% to 80% in ages <5, 52% to 62% in ages 5-64, and 62% to 75% in ages 65+. Results were similar in countries which implemented PCV10.
CONLUSIONS: Despite failing to meet the prespecified clinical endpoint for certain serotypes in immunogenicity trials, both PCV13 and PCV10 reduced incidence of disease for these serotypes in both the directly vaccinated and indirectly protected populations. This suggests that immunogenicity trial results may not be fully predictive of a PCV’s real-world impact on disease.
