The objective of a Post-Introduction Evaluation (PIE) is to evaluate the impact of adding a new vaccine to the existing immunization system in a country. In the past, it was recommended that PIEs take place 6–12 months after vaccine introduction. They are intended to assess the extent to which the vaccine introduction was successful or not, the challenges related to its implementation and the measures (if any) that need to be taken to improve introduction efforts (in relation to management, supply chain, data monitoring, etc.). With the growing burden on countries to conduct assessments and the growing experience that countries have in adding new vaccines, it is now recommended that if a country deems a PIE to be necessary, it should ideally be combined with the comprehensive EPI Review.

However, there may be circumstances in which it is preferable to conduct a PIE soon after introduction of the vaccine and not wait for an EPI Review, such as when a new vaccine formulation or delivery strategy is involved.

For example, as hepatitis B birth dose has characteristics that differ from other EPI vaccines – for example, delivery in the maternity ward and/or as part of postnatal care, and the timeliness requirement of 24 hours – a hepatitis B birth dose (HepB BD) PIE may not be as easily integrated with other reviews.

This tool is meant to be adapted and tailored to country context and objectives.

version: August 2026