Offering financial incentives for people to get vaccinated doesn’t work, according to a new study.

In fact, prizes and “negative messages” decreased vaccination rates among some groups, including people over 40 and fans of Donald Trump.

Led by Gov. Gavin Newsom, California offered the nation’s biggest pot of cash — $116 million — to entice people to get vaccinated against COVID-19.

“While messages increased vaccination intentions, none of the treatments increased overall vaccination rates,” the study concluded.

Under California’s vaccine incentive lottery, there were 30 winners on “$50,000 Fridays.” In addition, two million vaccinated Californians became eligible for$50 gift cards.

Research in Contra Costa County

As part of the research study, survey participants in Contra Costa County were offered nothing or $10 or $50 for getting vaccinated within two weeks.

Wrote the researchers: “Consistent with backlash concerns, financial incentives and negative messages decreased vaccination rates for some subgroups. Financial incentives and other behavioral nudges do not meaningfully increase SARS-CoV-2 vaccination rates amongst the vaccine hesitant.”

Professors from USC and UCLA and doctors with Contra Costa Health Services conducted the study.

Earlier Study Also Found Financial Incentives Didn’t Matter

The study echoed similar findings published Oct. 15 by the Journal of the American Medical Association. That study examined state lottery drawings of up to $1 million for getting COVID-19 shots and found they didn’t work.

At least 18 states have offered financial incentives for people to get vaccinated, according to the National Governors Association.

In addition to California, the state of Ohio jumped into vaccine incentive give-aways with both feet. Residents there who received at least one dose could win $1 million and full-ride college scholarships.

According to the CDC’s COVID-19 vaccination tracker, 67.2% of Americans 12-and-older are fully vaccinated. And, 77.7% in that age group have received at least one dose.