Australian preferences for influenza vaccine attributes and cost: a discrete choice experiment

Background People in Australia have access to different influenza vaccines, but may be unaware of available options and their features. There is a lack of preference studies for differentiated influenza vaccines including cell-based vaccines, particularly in Australia. This study investigated which influenza vaccine attributes people in Australia value, and the associated marginal willingness to pay (MWTP) using a discrete choice experiment (DCE). Methods Adults in Australia ineligible for free influenza vaccine, had been vaccinated in the last 5 years and intended to be vaccinated against influenza completed an online survey with a DCE. Participants were presented three influenza vaccine profiles described by eight attributes. Half of the DCE scenarios described influenza season severity to be the same as last year, and the other half as more severe. DCE data was analysed using a mixed multinomial logit (MMNL) model. Results N = 1203 adults completed the survey. All eight attributes significantly predicted vaccine choice ( p  < .05). Regardless of influenza season severity, preference was higher for a vaccine: with greater protection, designed to be an exact match to circulating influenza strains (match), using modern vaccine technology, manufactured by an Australian company, able to be received at a pharmacy, preferred by health care professionals (HCP), government funded for high-risk individuals, and having lower cost. Ranked on relative attribute importance, the top three were protection, match, and cost. Participants were willing to pay more for match and higher protection when simulating preference shares. The MWTP for the most important attributes, not including cost, were $1.61/$2.18 for each additional percent in protection (same/more severe season respectively), $25.37/$32.37 for match, and $4.06/$15.97 for HCP preference. Conclusions Taken together, findings suggest match, protection, cost and HCP preference are key influences on vaccine choice, highlighting the importance of shared decision-making.