Diagnosing the Reasons for Low Vaccine Take-up, and a Test of Potential Remedies
The first main contribution of this paper is to partially lift the veil on the reasons for low take-up of the flu vaccine. We provided information about flu vaccination using online messaging, across six college campuses (N=9,358). Our electronic messaging system tracks whether subjects decide to open e-mails
about flu vaccines; it provides an indicator for in-depth reading of e-mails; and it elicits self-reported intentions to get vaccinated. We match the e-mail campaign data to a second data source: information from campus health centers on whether or not individuals actually came in and got the vaccine.
Our results provide insights into the black box of vaccination decisions. We find that attention to information is surprisingly high, but take-up is still low. This is partly due to deliberate decisions against vaccination, but also partly due to people failing to follow through when they do have an intention to get the vaccine. Interestingly, lack of follow-through is more pronounced for individuals with lower college GPA.
A second contribution of the paper is an experimental test of three different types of interventions for improving flu vaccine take-up. Within each campus, subjects were randomized into one of four conditions: a control condition, a financial incentive treatment, a low-cost intervention based on peer endorsements, and a low-cost nudge that attempted to make sickness (or the benefits of vaccination) more salient through email. We find that the financial incentive that increased the near term benefits of vaccination significantly increased take-up. This is true even accounting for substitution from off-campus to on-campus vaccination. It appears to have worked by increasing exposure to information, swaying intentions, and improving rates of follow-through. Two novel, low-cost “nudges” did not affect take-up, but the nudge involving peer endorsement increased rates of opening e-mails, particularly if aligned with existing social ties (we measured social networks of our peer endorsers). These latter findings suggest that combining peer endorsements with other interventions (e.g., financial incentives) may be a good way to maximize exposure to the treatment.
[1] Seasonal influenza has a high mortality rate (Ward, 2013), and results in large numbers of hospitalizations (Thompson et al., 2003) and missed work days (Benson and Marano, 1998) each year.