(357) The Use of Background Incidence Rates to Support Vaccine Safety Monitoring: Challenges and Future Opportunities in the Framework of Beyond COVID Monitoring Excellence (BeCOME)

Background: BeCOME was initiated amongst safety science experts in 2022 to sustain the non-competitive collaborations during the COVID-19 pandemic. Background incidence rates (BIR) is one of seven focus areas of BeCOME. BIR of adverse events of special interest (AESI) were crucial for signal monitoring following global mass COVID-19 vaccination, especially for observed-to-expected analysis, but heterogeneity across estimates complicated their application and interpretation.

Objectives: To identify common challenges, possible solutions, and priorities across stakeholders for sustainable generation and use of BIR.

Methods: A vaccine industry working group on BIR was established, comprised of 8 pharmacovigilance and pharmacoepidemiology experts. The group reviewed challenges faced during the pandemic, performed a scoping review of key BIR publications to highlight knowledge gaps, and identified potential solutions and opportunities for multi-stakeholder actions. The preliminary challenges and key priorities were presented to other stakeholders at the inaugural BeCOME meeting held in June 2023 in Annecy, France and following a multi-stakeholder workshop, the priorities were ranked.

Results: Three major challenges were discussed: 1) various lists of AESI emerged and evolved during the pandemic, making rapid safety signal management difficult; 2) lack of harmonized methods and variations in approach to AESI algorithms and validation in real world data across large networks made it challenging to interpret results; and 3) since BIR can be influenced by factors such as age, sex, geography, time, and healthcare setting, the absence of stratified BIR brought difficulties in evaluating safety signals in different groups, sub-populations, and countries. To address these challenges, three top priorities requiring multi-stakeholder input were identified: i) establish a working group to enable sustainable delivery of BIR for a harmonized list of well-established and newly identified AESI for preparedness and scalability; ii) achieve agreement on best practices on the generation and application of BIR, addressing data quality, management of heterogeneity, and standardized reporting of data; and iii) improve the availability and granularity of data: based on demographics (e.g. age/sex strata, race), in specific sub-populations (e.g. pregnant people, high risk groups), and by geographic regions (e.g. low- and middle- income countries).

Conclusions: Currently, there is no common framework to estimate BIR to support vaccine safety monitoring. Through wide stakeholder engagement, consensus has been achieved on common challenges, with priorities being identified to support progress to best practices.