The question of how to motivate people to vaccinate is not just now occupying politics and science, but with particular urgency since effective vaccines against Covid-19 have become available.

One relies on persuasion, i.e. on education, to counter vaccine skepticism, but also on persuasion, for example on incentives or sanctions.

If one excludes compulsory vaccination, the question arises as to how the vaccination rate could be increased without being forced to do so.

Information campaigns alone have so far not brought the desired success.

In many countries, not only are the vaccination offers more accessible, for example pharmacies are included.

In addition, the health authorities keep reminding you of these options with letters and appointments.

Efforts of this kind to persuade the hesitant through a combination of easily accessible offers and non-binding but forcefully communicated advice refer to the idea of ​​“nudging”: If one cannot count on reasonable insight, then the limits of individual Use rationality with appropriate incentives to steer decisions in a certain direction.

If, for example, convenience prevents you from acting rationally for your own benefit, a cash prize or a sweepstakes can provide the necessary "nudge" in the desired direction.

However, since money cannot be distributed indefinitely for every action, it is of interest to see how the right words can be used to give people a nudge.

In a comprehensive experiment, an American research group has investigated how the willingness to be vaccinated can be increased by addressing them appropriately.

Through cooperation with the Walmart group, in whose pharmacies flu vaccinations are given, around 700,000 patients who had been vaccinated in the past but had not yet received the current flu vaccination could be contacted.

The aim was to examine how different text messages reminding of the upcoming vaccination would have an impact.

The 22 variants differed in their information and appeal content: some contained only a simple reminder of the current vaccination offer.

Others emphasized the protective effect for themselves and others.

Others suggested majority orientation (“More Americans than ever are getting the vaccine this year”) or attempted to garner attention with a joke (“You know that flu joke? Never mind, we don’t want to spread it” ).

Some text messages were interactive and awaited an answer, while others were sent several times without being asked.

In the run-up, both the experts who had helped formulate the notifications and randomly selected respondents were asked for their assessments of which messages would probably increase the willingness to vaccinate.

Both groups predicted an increase that was not far from the actual result: the proportion of those who were vaccinated again increased by almost ten percent after a reminder.

The laypersons estimated more accurately than the scientists how effective the different interventions would be.

However, neither group identified the most successful text message.

They tapped different variants of the message that the flu vaccine protects others - sometimes with, sometimes without reference to the burden on hospitals caused by the Covid 19 pandemic.

That repetition pays is not surprising.

But it is true that simple messages without arguments have the best effects.

This fits in with a thesis by the sociologist Niklas Luhmann that action in modern society is often based on “consequential rationality” instead of on moral and normative reasons: one waits for someone else to make a decision in order to then base one’s own decision on it.

The most successful messages in the experiment inform that, thanks to a decision made by others, one enjoys the privilege of an already reserved vaccine dose - but can still choose whether to take it up or not.

For enough numbers, this is an offer you can, but don't have to, refuse.