Post-marketing vaccine safety surveillance, including both passive and active surveillances, aims to detect and alert to signals of adverse events following immunization (AEFI), and to further ensure public safety and public confidence in vaccination. Active surveillance could proactively seek information of AEFI and timely investigate the potential safety signals, therefore, it has become the main development trend of post-marketing surveillance worldwide. Nowadays, there is an ongoing interest in developing active surveillance systems that can incorporate and use existing electronic data such as administrative claims and electronic health records. Researchers have also began exploring ways of accruing data closer to "real-time" in order to speed the recognition of potential safety problems.This near real-time vaccine safety surveillance is gradually emerging worldwide. This study reviews the development and methodology of near real-time surveillance and aims to accelerate the foundation of the active surveillance system for vaccine safety in China.

Vaccine; Safety; Active surveillance; Near real-time; Sequential probability ratio test