Some studies showed that young adults have lower intentions of COVID-19 vaccination than older people. Our previous study found that nudge-based messages providing information on others’ decisions and behaviors could strengthen the vaccination intentions of the older people, but do not have the same effects for the young adults (Sasaki, Saito, & Ohtake, 2021). In other words, we have not yet found an effective message to encourage the vaccination of the young adults.
This study again explores nudge-based messages that can encourage COVID-19 vaccination of young adults with low vaccination intentions at baseline. Our preliminary analysis indicates the possibility that the high need for going out and a rise in altruism among younger people may close the gap in vaccination intentions between older and younger people. One foreign study reported that the message, “Full shot reserved for you,” has a large effect in promoting people to receive the seasonal flu vaccine (Milkman et al., 2021). The similar message may be effective for promoting COVID-19 vaccination of people in Japan. Taking the pre-analysis and the foreign study into account, we will develop nudge-based messages for the vaccination of young adults in Japan.
Collaborating with a local government in Japan, we conduct a field experiment toward 4,000 young adults (30-39 years old) residing in that area. In the experiment, we randomly divide the subjects into either of one control group or three treatment groups. The local government mails coupons, which are required for COVID-19 vaccination bookings and post-vaccination records, to their residents. In the treatment groups, we respectively put a sticker with a nudge-based message on the envelope to mail the coupons.
The local government merge information on which group they belong to, whether they receive the COVID-19 vaccine, and when they receive it, and share the list with us, the research team, after it has been completely anonymized.
Our first analysis evaluates the impacts of three nudge-based messages on the likelihood that the subjects receive the COVID-19 vaccine, by using the linear probability model, etc. Our second analysis evaluates the messages’ impacts on the timing of when they receive it, by using the Cox's proportional hazards model, etc.
- Sasaki, S., Saito, T., and Ohtake, F. 2021. Nudges for COVID-19 voluntary vaccination: How to explain peer information? Osaka University Discussion Papers In Economics And Business, No.2107.
- Milkman, K.L. et al. 2021. A Mega-Study of Text-Based Nudges Encouraging Patients to Get Vaccinated at an Upcoming Doctor’s Appointment. Proceedings of the National Academy of Sciences, 118(20), e2101165118.