A Technical Expert Consultation on optimizing pneumococcal conjugate vaccine (PCV) impact was held at World Health Organization (WHO) Headquarters June 12-13, 2017. Since licensure and prequalification in 2000, PCVs have been introduced in 141 countries and 190,000 pneumococcal deaths have been averted from 2000 to 2015. WHO recommends that the two prequalified PCV products, 10-valent (PCV10) and 13-valent (PCV13), should be administered either in a three primary doses (3p+0) or two primary doses with a booster (2p+1) schedule. Catch up vaccination is recommended as a mechanism to accelerate herd protection.
An increasing amount of evidence has accumulated since the last PCV position paper update in 2012, including from low and middle-income countries. The meeting served to review new evidence that could inform the Strategic Advisory Group of Experts Working Group for PCVs (SAGE PCV WG) of possible differences in impact and effectiveness by product and schedule for both routine infant immunization and catch-up immunization. Throughout the meeting, participants identified critical data gaps and developed a prioritized list of future PCV research directions.
Both primary evidence and modeled data were reviewed in the consultation to formulate overarching conclusions, identify data gaps, and prioritize future research questions. The meeting discussed evidence presented from PCV Review of Impact Evidence (PRIME)—an extensive systematic review of PCV impact data which was created in part to serve as an evidence base for SAGE PCV WG. The empiric evidence reviewed on immunogenicity, nasopharyngeal carriage, pneumonia, invasive pneumococcal disease, and mortality is discussed in a separate report available on the WHO SAGE website. The systematic review found a lack of available evidence to conclude a strong preference for either PCV product or schedule due to both
confounding factors across different environments and a distinct lack of head to head studies which directly compared products and/or schedules.
The participants reviewed data and discussed the programmatic implications related to a 3p+0 or 2p+1 schedule or shifting from a 3p+0 to a 2p+1 schedule. The evidence for the added value of introducing catch-up campaigns, including the age groups to be targeted, based on mathematical models, was also discussed. To fully capture the global impact of PCVs, comprehensive modeling work for both schedules and product choices in the future will require empiric evidence from a wider range of geographic regions.
Representatives from high, middle and low-income countries highlighted the drivers of decision making regarding choice of PCV product, dosing schedule, and the use of a catch-up campaign through presentations and a panel discussion. While each country shared unique experiences, common themes that influenced decisions across all settings included the importance of cost-effectiveness, the availability of local impact data, vaccine supply, and cold chain storage capacity.
The conference culminated with individual participants identifying the three highest priority research questions needed to make or affirm policy recommendations. The majority of participants recommended research topics that centered on product choice and schedule. Additionally, the participants consistently cited serotype replacement and serotype distribution as an emerging concern and pressing research gap. The presented evidence and prioritized research recommendations were taken into consideration at the PCV SAGE WG meeting, which occurred directly after the consultation.
- SAGE background document
- Pneumococcal disease