A nurse holds a vial of the Pfizer-BioNTech COVID-19 vaccine at Guy's Hospital in London on Tuesday. (Photo: ASSOCIATED PRESS)

People aren’t always great at predicting precisely how they’ll behave in the future. That’s one of the reasons it’s tricky to poll them on hypothetical questions, whether it’s asking if they’ll vote in an election or ― more relevant at the moment ― if they’ll take a coronavirusvaccine.