It's a question that's more pertinent than ever in the wake of the coronavirus pandemic, but a new study suggests that forcing people into getting jabs could become counter-productive.

Participants were asked how likely they were to get vaccinated, based on whether the vaccinations were enforced by law or voluntary: During both waves, people were more likely to want to get vaccinated if they didn't have to, but the gap was bigger the second time around.

There's something else going on as well though, the team behind the study suggests: When vaccines are voluntary, more people are persuaded to take them as they see friends and family getting jabbed.

"How people feel about getting vaccinated will be affected by enforcement in two ways – it could crowd out pro-vaccine feelings, and reduce the positive effect of conformism if vaccination is voluntary," says psychologist and behavioral economist Katrin Schmelz, from the University of Konstanz in Germany.