Did the ‘Million Dollar Vax’ prize work in Australia?

Almost a year ago, one lucky student walked away with $1 million after entering the ‘Million Dollar Vax’ competition to drive up Australia’s COVID-19 second-dose vaccinations.
Financial incentives have already been used to boost childhood immunisation rates, but never in the form of a competition with cash prizes, and certainly not targeted at adult vaccination.
The gamble appears to have “nudged” entrants to complete their two-dose schedule of COVID-19 vaccines, say researchers from the University of Melbourne.
Writing in BMJ Open, they reported that those who entered the competition were about 2.3 times more likely to be vaccinated than those who did not enter.