Monitoring vaccine safety: a critical component of every immunisation program

Consumer reporting of adverse events following immunization

Surveillance of adverse events following immunisation (AEFI) is an essential component of vaccine safety monitoring. The most commonly utilized passive surveillance systems rely predominantly on reporting by health care providers (HCP). We reviewed adverse event reports received in Victoria, Australia since surveillance commencement in July 2007, to June 2013 (6 years) to ascertain the contribution of consumer (vaccinee or their parent/guardian) reporting to vaccine safety monitoring and to inform future surveillance system development directions. Categorical data included were: reporter type; serious and non-serious AEFI category; and, vaccinee age group. Chi-square test and 2-sample test of proportions were used to compare categories; trend changes were assessed using linear regression. Consumer reporting increased over the 6 years, reaching 21% of reports received in 2013 (P<0.001), most commonly for children aged less than 7 years. Consumer reports were 5% more likely to describe serious AEFI than HCP (P=0.018) and 10% more likely to result in specialist clinic attendance (P<0.001). Although online reporting increased to 32% of all report since its introduction in 2010, 85% of consumers continued to report by phone. Consumer reporting of AEFI is a valuable component of vaccine safety surveillance in addition to HCP reporting. Changes are required to AEFI reporting systems to implement efficient consumer AEFI reporting, but may be justified for their potential impact on signal detection sensitivity.

Parent perspectives on consent for the linkage of data to evaluate vaccine safety: a randomised trial of opt-in and opt-out consent

BACKGROUND

We examined parents' consent preferences and understanding of an opt-in or opt-out invitation to participate in data linkage for post-marketing safety surveillance of childhood vaccines.

METHODS

A single-blind parallel-group randomised controlled trial: 1129 families of babies born at a South Australian hospital in 2009 were sent information at 6 weeks post-partum, explaining data linkage of childhood immunisation and hospital records for vaccine safety surveillance, with 4 weeks to opt in or opt out by reply form, telephone, or email. At 10 weeks post-partum, 1026 (91%) parents were followed up by telephone interview.

RESULTS

In both the opt-in (n = 564) and opt-out arms (n = 565), four-fifths of the parents recalled receiving the information (81% vs. 83%, P = 0.35), three-fifths reported reading it (63% vs. 67%, P = 0.11), but only two-fifths correctly identified the health records to be linked (43% vs. 39%, P = 0.21). Parents who actively consented (opted in) were more likely than those who passively consented (did not opt out) to recall the information (100% vs. 83%, P < 0.001), report reading it (94% vs. 67%, P < 0.001), and correctly identify the data sources (60% vs. 39%, P < 0.001). Most parents supported data linkage for vaccine safety surveillance (94%) and trusted its privacy protections (84%). Most parents wished to have minimal or no direct involvement, preferring either opt-out consent (40%) or no consent (30%). A quarter (24%) of parents indicated opt-in consent should be sought; of these, 8% requested consent prior to every use, 5% preferred to give broad consent just once and 11% preferred periodic renewal. Three-fifths of the parents gave higher priority to rapid vaccine safety surveillance (61%) rather than first seeking parental consent (21%), and one in seven was undecided (15%). Although 91% of parents reported that their babies were fully immunised (76%) or under-immunised (15%), and trusted vaccines as safe (90%), three-fifths (62%) were very or somewhat concerned about serious reactions.

LIMITATIONS

The context of data linkage is limited to vaccine safety surveillance. Only recall and understanding retained at 1 month post enrolment were measured.

CONCLUSIONS

This trial demonstrates that informed consent for a population-based surveillance programme cannot realistically be achieved using mail-based opt-in and opt-out approaches. While recall and understanding of the study's purpose were better among parents who actively consented (opted in) compared with parents who passively consented (did not opt out), participation was substantially lower (21% vs. 96% respectively). Most parents appeared to have a poor understanding of data linkage for vaccine safety surveillance; nonetheless, they supported data linkage. They preferred a system utilising opt-out consent or no consent to one using opt-in consent.

Parental perspectives of vaccine safety and experience of adverse events following immunisation

INTRODUCTION

We aimed to determine demographic predictors of parental vaccine safety and risk perceptions, and assess the relationship between the occurrence of children's perceived adverse events following immunisation (AEFI) on parents' opinions.

METHODS

Computer-assisted telephone interviews (CATI) were conducted in 2011 with a cross-sectional, random general population sample of rural and metropolitan residents in South Australia. Multivariate ordinal logistic regression analyses examined associations between parental vaccine safety attitudes and socio-demographic factors, adjusting for whether children had ever experienced a previous suspected AEFI.

RESULTS

Of 469 parents interviewed, 95% were confident in vaccine safety in general, but almost half expressed concern for pre-licensure testing of vaccines. Of all parents, 41% responded that at least one of their children had experienced an AEFI. Almost one third of the AEFI parent group indicated they reported their children's symptoms to either a healthcare professional or the Department of Health. Parental acceptability of the risks of febrile convulsion and anaphylaxis were 73% and 76% respectively. Ordinal logistic regression analyses showed parents of children who had experienced a suspected AEFI were associated with greater concern for vaccine safety (OR:0.53, p≤0.01) and more were likely to expect either a mild or a serious AEFI. After adjusting for demographics, 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 the two vaccine risks presented: febrile convulsion (OR:0.57, p=0.04) and anaphylaxis, (OR:0.55, p=0.04).

CONCLUSIONS

Parents commonly perceive and report that their child has experienced an AEFI. In this group of parents the subsequent expectation of an AEFI and vaccine safety concerns may be heightened. Further research should investigate parental understandings of differentiating an expected event from an adverse event as this could inform immunization risk communication and consumer AEFI reporting strategies.