On the contextual nature of vaccine safety monitoring: Adverse events reporting after HPV-vaccination in Denmark, 2015.

Abstract

BACKGROUND\nIn 2013-15, Denmark experienced an increase in reported suspected adverse events following vaccination (AEFI) against human papilloma virus (HPV). Dedicated centres ( One Access ) were established in order to standardize management of patients who experienced medically unexplained physical symptoms after HPV vaccination. Since One Access was targeted patients with suspected AEFI after HPV vaccination, we used this opportunity to estimate completeness in AEFI reporting to the Danish Medicines Agency (DMA), and explore the topic of AEFI reporting from the perspective of physicians working at the centres to better understand health professionals reporting behaviour.\n\n\nMETHODS\nThe study consisted of a quantitative and a qualitative part. In the quantitative analysis, we used the Danish civil registry number to merge a line-list of all One Access patients referred in 2015 with total number of patients who had reported suspected serious AEFI following HPV vaccination to the DMA in the years 2009-2015. We conducted four semi-structured interviews with doctors representing three out of five regions. The Theoretical Domains Framework together with empirical data from two clinical fieldtrips guided the formation of the qualitative study.\n\n\nRESULTS\nAmong 1577 One Access patients, only 404 (26%) were reported to the DMA. We found significant regional differences in reporting completeness (p\u202f<\u202f0.001) and differences between regions when looking at reporters backgrounds (healthcare professionals vs non-professionals; p\u202f=\u202f0.004). We identified several factors of importance for reporting behaviour amongst physicians, mainly under the domains of Knowledge, Motivation & Goals, and Environmental Context.\n\n\nCONCLUSIONS\nDespite an official aim of homogenous case management, reporting of suspected AEFI was incomplete with large regional differences. The qualitative study corroborated that reporting behaviour was contextual. This observation represents an important caveat in interpreting data from AEFI reporting, in particular when these data are used for research or policymaking.