Core variables for AEFI
For optimal vaccine safety monitoring and meaningful analysis of Adverse Event Following Immunization (AEFI) data, systematic and standard collection of critical parameters is essential. A limited number of variables are required to properly manage AEFI information. This includes a unique identification of the report, the primary source of information, patient characteristics, details of the event(s) and vaccine(s) of interest and the possibility of collecting additional information if needed.
Comparing AEFI reporting forms from a sample of emerging countries, a WHO working group developed a core data set that was endorsed by the Global Advisory Committee on Vaccine Safety (GACVS) in June 2012. This data set includes 22 variables with 10 identified as critical. This simple structure is expected to provide countries with a harmonized template that will simplify AEFI reporting and allow for comparisons and pooling of essential information for action.
A sample reporting form incorporating the core variables identified has been developed. This could guide countries when they develop new AEFI reporting forms for their immunization programs. The core variables would also enable countries to develop standard linelists. The Global Vaccine Safety Team is currently using the core variables to develop a computer based application to collect AEFI data that could be easily tailor-made to country specific requirements and/ or integrated with country’s existing HMIS systems. This will ensure harmonization of AEFI data collected and encourage pooling of information from multiple sources so that signals of rare and very rare adverse events can be identified.