Vaccination requirements are a matter of course in many countries. An overview in the journal "Vaccine" offers a more detailed international comparison and shows at least one mandatory vaccine for more than one hundred countries even before the start of the Covid 19 pandemic. Sanctions range from fines and imprisonment to the temporary loss of parental custody, for example in Italy. Most of the time, childhood vaccinations are affected, so that many sanctions relate to attending care and educational institutions. The result is usually not only an increase in the vaccination rate, but also increased confidence in the vaccines: In France, the previously widespread vaccination skepticism fell significantly after the number of mandatory vaccinations for children had increased from three to eleven in 2018.

Against the background of such experiences, in retrospect it may have been a mistake to rule out compulsory vaccination against Covid-19 in Germany. But at least for a certain time this position could not only claim to take the wind out of the sails of the growing protest against a "Corona dictatorship", but also to make a decision-theoretic argument: If a vaccine is so good that it is protects against disease or even infection, this benefit would motivate enough people to get the injection anyway.

But this thesis, often put forward by economists against the compulsory vaccination, must fail if there are too many who do not believe in the effectiveness and safety of the vaccine - or if the focus is not on the individual benefit but on the collective protective effect.

So-called herd immunity is a public good: you benefit even if you have not contributed to it yourself.

In such a situation there is no need to be vaccinated.

A rational calculation and a little convenience are enough to free-rider.

On the best way to vaccination protection

Using data from the Socio-Economic Panel (SOEP) from 2020, a team of researchers from the German Institute for Economic Research in Berlin and the Karlsruhe Institute of Technology examined whether consent to vaccination was sufficient to make it voluntary - and whether mandatory vaccination was acceptable would come across. The data confirm a willingness to vaccinate, consistent with other surveys and the actual vaccination quota, of around 70 percent and a divided opinion on mandatory vaccination, which at that time around half would have welcomed and the other half rejected.

The respondents are divided into four groups: the largest group, those in favor of vaccination, agreed to both voluntary and compulsory vaccination;

Opponents of mandatory vaccination wanted to be vaccinated, but refused a duty;

those who oppose the vaccination want to be vaccinated neither voluntarily nor compulsorily;

and the "passengers" would prefer not to be vaccinated, but advocate compulsory vaccination.

A paradoxical attitude

It is surprising that of those who do not want to be vaccinated voluntarily, at least 27 percent belong to the "passengers" who vote for a general vaccination requirement. Some of them are people who cannot be vaccinated for medical reasons. But there are obviously people who, precisely because of their own rejection, assume that coercion is necessary. This group considers - in contrast to the vehement opponents of vaccination - the virus to be dangerous. The authors suspect that they are free riders who want to make sure that others ensure an adequate vaccination rate. But this attitude would be paradoxical, as the coercion would ultimately deprive them of the possibility of free-riding.

Why can some people not bring themselves to be vaccinated, but would welcome an order? To be aware of one's own weaknesses and therefore to advocate external coercion, has a literary model: Odysseus, who lets himself be tied to the mast of his ship so that he cannot follow the sirens' songs into perdition. When it comes to vaccination, however, it is not enough to be prevented from doing something. You have to do something that you refuse.

The external compulsion then at least offers the possibility of sticking to a consistent self-presentation: What one does not do voluntarily, one does not have to be accounted for as a personal act.

A compulsory vaccination would protect the self-portrayal of those who have already committed themselves to skepticism: They could act without the involvement of their own personality and thus have both - a clear conscience and vaccination protection.