Postmarketing vaccine safety passive surveillance: an exploratory study of parent and healthcare provider reporting of adverse events following immunisation (AEFI)

Abstract

Monitoring the safety of new and exisiting vaccines following licensure is a critical component of maintaining public confidence in immunisation and is an integral part of national immunisation programs. In Australia the process relies predominantly on the passive surveillance of adverse events following immunisation (AEFI) via spontaneous voluntary reports of AEFI by healthcare professionals, vaccine manufacturers and the public to state or federal health authorities. The aim of this thesis was to investigate factors that promote or inhibit parental and healthcare professional reporting of AEFI. A mixed-methods sequential study design was employed, with three separate studies conducted: two quantitative and one qualitative. The first quantitative study involved telephone interviews of a representative sample of 469 South Australian parents, recruited from the general population about the previous occurrence of children’s AEFI, safety opinions, awareness of surveillance and reporting AEFI to healthcare professionals and surveillance authorities. The second quantitative study interviewed 179 parents whose children had experienced an AEFI and had reported the events to the South Australian Immunisation Section, Department of Health. This study was conducted following the national suspension of a seasonal trivalent influenza (STIV) vaccine in 2010. Parental vaccine safety attitudes, reasons for reporting and impact on future vaccination intent were assessed. The qualitative study involved in-depth interviews with 29 healthcare professionals working in general practice, council immunisation clinics and a paediatric hospital emergency department (ED). The interviews sought to examine the experiences, knowledge and training of general practitioners (GPs), nurses and ED consultants in detecting AEFI and of reporting to surveillance authorities. The study was planned using a social constructionist perspective and thematic analysis was used to analyse the interview data. In the first study, 95% of all parents were confident in vaccine safety in general. Parental confidence in vaccine safety was significantly associated with higher levels of education (OR:2.58, p = 0.01) and being born in Australia, (OR:2.30, p = 0.004). Mothers, when compared with fathers, were less accepting of two vaccine risks: febrile convulsion (OR:0.57, p = 0.04) and anaphylaxis, (OR:0.55, p = 0.04). One in four parents stated that at least one of their children had previously experienced an AEFI: one third of these parents reported the symptoms to either a healthcare professional or the Department of Health. Parents of children who had experienced an AEFI were less likely to believe vaccines were safe (OR:0.53, p≤0.01) compared with parents of children who did not experience an AEFI. In the second study, 88% of all parents were confident in the safety of vaccines in general. Parents reporting an AEFI to the 2010 STIV were more likely to state the event had influenced future vaccination intent than the National Immunisation Program (NIP) vaccine parent AEFI reporters (65% vs 14%, p<0.001), with 63% stating refusal or hesitance to re-vaccinate their children against influenza. Concern for their children’s symptoms and media reports of the 2010 STIV program suspension were the most common reasons for reporting. The qualitative study revealed that interpretations of a “serious” or “unexpected” AEFI and what would constitute a reportable AEFI varied according to the professional group. Common barriers to reporting included time constraints and unsatisfactory reporting processes. Nurses were more likely to have received formal training in vaccine safety and reporting than medical practitioners. Collectively, these studies should inform future strategies aimed at improving AEFI reporting. These need to incorporate ongoing education and enhancing existing reporting processes for health professionals and investigation of alternate surveillance approaches that consumers will use.