Influenza is a major cause of death worldwide. In an attempt to decrease the morbidity and mortality associated with influenza, as well as its financial cost and burden to healthcare services, the influenza vaccine has been offered to children in England since 2013. However, uptake is low. Fear of side-effects has been well-established as one of the major factors contributing to vaccination refusal. But not all side-effects perceived after vaccination can be attributed to the vaccine. Multiple psychological factors related to the ‘nocebo’ effect may influence parental perception of side-effects from vaccination. The role of cognitive biases and heuristics in vaccination has been well-explored. However, there is no research investigating whether information processing biases are associated with vaccination behaviours. In this thesis, I aimed to identify psychological factors which were associated with uptake of the child influenza vaccine and parental perception of side-effects from vaccination. I conducted a nationally-representative online survey of parents of vaccine-eligible children in the 2015/16 influenza season (n=1001). Results suggested that believing that the vaccine caused adverse effects were associated with not vaccinating one’s child and perceiving side-effects from vaccination in those who did vaccinate. However, the cross-sectional nature of this study made it difficult to infer causality. To better investigate predictors of parental perception of side-effects from vaccination I conducted a prospective cohort study in the 2016/17 influenza season (n=270); the last follow-up was at the end of the 2017/18 influenza season (n=232). I found that multiple psychological factors were associated with parental perception of side-effects from vaccination. In particular, pre-vaccination expectations were strongly associated with perceiving side-effects from vaccination. I also investigated rates of re-vaccination for influenza in the 2017/18 season and factors associated with re-vaccination. Results indicated that over one in six children were not re-vaccinated for influenza in 2017/18. Perceived severity of side-effects from vaccination in 2016/17, and parental worry about side-effects perceived, were associated with not re-vaccinating one’s child in the 2017/18 season. While many studies have identified that parental perception of side-effects plays a major role in vaccination refusal, few studies have investigated potential causes of parental perception of symptoms. My results indicate that managing parents’ expectations about the incidence and severity of vaccine side-effects may decrease parental perception of side-effects from vaccination. Decreasing worry about side-effects perceived may increase vaccine uptake and re-vaccination rates. These are novel targets for vaccine communications and interventions.
|Date of Award
|1 Jul 2019
|James Rubin (Supervisor) & Jenny Yiend (Supervisor)