Reasons for excluding adverse events in cost-effectiveness analyses of vaccines: A survey amongst authors

Although vaccines must adhere to the strictest safety standards in medicine, adverse events (AE) do occur occasionally. Even when clinically negligeable, these AE can still have health-economic implications, affecting the cost-effectiveness of vaccines. A review revealed that only 25 % of recent health-economic studies on childhood vaccines incorporated AE. In this study, we reached out to all corresponding authors of the reviewed articles who excluded AE to understand their rationale for exclusion (response rate 40 % (27/67)). The predominant reasons for not including AE were (1) that these were deemed too rare and insufficiently relevant (17/27, 65 %), (2) analysts adhered to previous methodologies that excluded AE (10/27, 35 %) and (3) there was a lack of sufficient data (9/27, 33 %). We argue that AE deserve more attention from analysts and that more efforts are needed to develop conceptual methods and collect data that enable meaningful incorporation in CEAs.