“Claim your dose”

Overcoming psychological barriers to vaccination remains a significant hurdle for COVID-19 vaccination efforts. Any given COVID-19 news feature will remind you that vaccine hesitancy is rife, especially in countries such as the United States. Compounding the issue further, even those who fully intend to get their jab can be forgetful or procrastinate, further hampering efforts to get shots in arms.

As such, it's vital to develop an effective toolbox to make it as effortless and appealing as possible for patients to book and turn up for their appointments. And though they may seem insignificant, one of the most useful behavioural nudges we have at our disposal is the mighty reminder message.

Crafting the wording of a reminder that packs a punch is no easy feat. As with most things in psychology, individual differences can greatly affect the response to any given nudge. But, thanks to research from Hengchen Dai at UCLA and team, we now have a better impression of how text-message reminders can impact vaccine uptake, as well as how to word them.

Their study, published in Nature, describes two sequential randomised control trials on the topic. In the first study, the investigators recruited a massive 93,354 participants who had received an initial notification that they were eligible for their vaccine. The team randomly allocated participants in a 4:1 ratio to either a group that was sent a booking reminder text-message one day later, or a control group that received no reminder message.

Within the group that received the message, the authors looked at how different types of information provision and language affected uptake. All messages included two main points: a reminder of vaccine availability, and a link to an appointment scheduling website which allowed participants to book their slot right away. A subset of these also included language intended to induce a feeling of ownership over vaccines — specifically, the phrase "claim your dose". This isn't the first time this approach has been used; similar phrasing has been shown to increase uptake of flu vaccines.

To combat hesitancy and misunderstandings, a two-minute video aiming to dispel common vaccine misconceptions was also provided alongside a subsection of reminder messages, both with and without ownership induction phrases. Unfortunately, the authors note that only 21% of participants actually chose to watch it.

The team were interested in whether or not participants booked their vaccination appointment within six days following the first reminder, and whether they actually turned up and got their first dose within four weeks of the reminder. And they found that the messages worked: only 7.2% of those who didn't receive a reminder booked within those six days, but this increased by 6.07 percentage points among those who received a reminder. Similarly, 13.89% of the non-reminder group had received their vaccine within four weeks, but this increased by 3.57 percentage points among those who received the text message.

Better yet, the reminders containing language inducing feelings of ownership over the vaccines appeared to be most effective, boosting appointment and vaccination rates by 6.83 and 4.13 percentage points, respectively, relative to those that received no reminder. This provides a strong endorsement for this type of phrasing in vaccination reminders.

Though these results are very promising, the study found no evidence to suggest that provision of information addressing vaccine hesitancy alongside these reminders was more effective at increasing uptake. However, given the small number of participants who actually watched the videos, this topic merits further investigation.

The second RCT (N=67,092) looked at additional reminder messages, sent eight days after initial vaccine eligibility to those who had not yet booked their first dose and may have been procrastinating or hesitant. The second, further reminder increased booking and vaccination rates by 1.65 and 1.06 percentage points, respectively, compared to those who didn't get a second message.

Further studies will be needed to fully understand whether this approach holds across other cultures outside of California. Establishing a feeling of ownership over vaccination decisions may be more or less motivating in different countries, and even in different areas within the United States, which could significantly affect the potency of this approach. Within this study, at least, analyses suggest that these increases in uptake were not largely affected by race or age, which may be promising for wider application.

Overall, these findings inform the design of behavioural nudges for promoting health decisions. Not only are reminders clearly valuable tools in our arsenal, but wording that is crafted to induce feelings of ownership over vaccines appears to be particularly effective in increasing uptake. Adopting this as a standard approach for COVID-19 vaccine messaging in the USA, the authors estimate, could result in an additional 4.73 to 7.42 million people taking up the vaccine within a month of the reminder.

In a moment where even small increases in vaccine uptake can have a tangible impact on the health of the population, research such as this serves to underline the impact that psychology can have when practically applied.

Further reading

– Behavioral Nudges Increase COVID-19 Vaccinations

About the author

Emma L. Barratt (@E_Barratt) is a staff writer at BPS Research Digest