Do vaccine lotteries like Louisiana's work? One study offers clues.

As COVID-19 vaccination rates continue to fall, several states have spent millions of dollars on lottery prizes to encourage unvaccinated Americans to get their shot.

The million-dollar question: Do they work?

Public health experts say that while lotteries may nudge some people to get vaccinated, most won't be convinced.

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The small chance of winning a big windfall isn't enough to sway the majority of unvaccinated Americans who strongly oppose the vaccine, have safety concerns or don't want their daily lives disrupted by the vaccine's side effects, they say.

“For certain segments of the population, (lotteries) can be useful,” said Robert Bednarczyk, associate professor of global health and epidemiology at Rollins School of Public Health at Emory University. "But it really comes down to, who are you trying to reach and how can you reach them?"

First lady Donna Edwards and Gov. John Bel Edwards unveil a giant check during a news conference June 17 at the Louisiana State Capitol in Baton Rouge.  They  announced that Louisiana will participate in a lottery, giving cash prizes and scholarships to residents who have been vaccinated against the coronavirus.

Louisiana recorded a 14% jump in vaccinations first week after announcing its $1 million grand prize lottery June 17, but the rate was nowhere near its spring peak and has since tapered off, The Advocate of Baton Rouge reported.

State health officials cautioned against using the data to measure the impact of its Shot At A Million campaign because there’s sometimes a two- to- three-week delay between when a shot is administered and when the state’s online dashboard is updated, the newspaper reported.

And nobody has studied specifically how the vaccine rate might have been different in Louisiana without the lottery.

Where Louisiana stands

As of Thursday, about 39% of the state's 4.6 million residents had received at least one dose of the vaccine, the nation's second lowest percentage, behind only Mississippi, according to data from the U.S. Centers for Disease Control and Prevention. Louisiana was tied for the second-lowest percentage of residents who are fully vaccinated at 35%.

Some states already have declared their vaccination lotteries a success. 

The California Department of Public Health said the state saw a 33% increase in vaccinations after announcing "Vax for the Win," administering an average of 121,000 doses each day the first week of the program and about 161,000 daily doses the following week.

Nearly 3.5 million Ohioans entered the state's "Vax-a-Million" drawing to win one of five $1 million prizes. Ohio Gov. Mike DeWine called it "a resounding success," citing a 44% increase a week after its launch.

But a recent study suggests the governor's office may have been premature in declaring victory. 

Researchers at Boston University School of Medicine found Ohio’s lottery did not increase COVID-19 vaccination rates when compared with other states without lottery-based incentive systems, according to the study published July 2 in JAMA Network.

“When we heard the early reports that the lottery worked, we were a little skeptical,” said lead author Dr. Allan J. Walkey, professor of medicine at Boston University School of Medicine and a physician at Boston Medical Center.

Using data from the Centers for Disease Control and Prevention, study authors examined adult vaccination rates in Ohio four weeks before and afterthe lottery was announced and compared them with rates in states across the U.S.

While the decline in Ohio’s vaccination rates slowed after the lottery announcement, it slowed even more in other U.S. states during the same time frame.

“Ohio was following the same trends as the rest of the country,” Walkey said.

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Questioning the study

DeWine's press secretary, Dan Tierney, told USA TODAY that the study was flawed because it used CDC data that reflected when dose administrations were reported, not whenthey were given.

"Our data does not reflect the continued decline the BU study graphs claim to show," he said. "We believe the Ohio data based upon first dose start date is the most accurate measure, and that data clearly shows a significant increase after the 'Vax-a-Million' announcement."

The study also didn't include vaccination rates among 16- and 17-year-olds, who were eligible for a scholarship lottery under the same program. 

Walkey, the study's author, argues other factors may have increased the state's vaccination rates. 

A few days before Ohio announced its lottery on May 12, the Food and Drug Administration expanded authorization of Pfizer’s COVID-19 vaccine to include adolescents over 12 years old. Walkey said the FDA’s action – not the lottery – may have slightly increased vaccination rates in Ohio and other parts of the U.S.

Though researchers looked only at vaccination rates among those over 18, Walkey says adults may have been more motivated to get their shots after younger teens became eligible.

"There's something potentially to that," said Bednarczyk, who was not affiliated with the BU study. "If (teens) are advocating for themselves, that may have the effect of pulling their parents along with them or it may turn into a family type of thing like, 'We can all get vaccinated together.'"

'Good initial look'

The study is a "good initial look at the data," but he says more research is needed to determine whether lotteries are successful at increasing COVID-19 vaccinations. The study may be masking the success of Ohio’s lottery program at the hyperlocal level.

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“When we look at these types of big picture studies trying to look at overall vaccination rates in a state, it’s tough to really understand what’s happening because even within the population of a state, there may be some pockets of individuals that are more motivated,” Bednarczyk said.

Aside from Louisiana, multiple other states followed Ohio’s lead and implemented lotteries to encourage COVID-19 vaccinations, including Maryland, New York, New Mexico and West Virginia.

However, prizes alone won’t convince the remaining unvaccinated Americans to get their COVID-19 shot. They must be coupled with traditional public health strategies that incorporate community leaders, county health departments, education, and consistent outreach, experts say.

“Where lotteries might work best is a situation where there are lots of people on the fence who don’t have strong feelings about the vaccine,” Walkey said. “Lots of people are not like that … and a small chance of winning money is probably not the type of incentive that’s going to change people with very strong vaccine beliefs.”

How to enter Louisiana's vaccine lottery

Louisiana is offering a chance at a $1 million grand prize jackpot and another $1.2 million in other prizes for vaccinated residents who enter its Shot At A Million lottery.

Weekly drawings each Wednesday, starting July 14, will offer vaccinated adults a chance at a $100,000 prize and residents 12-17 a chance at a $100,000 college scholarship.

The $1 million grand prize winner, along with winners of five $100,000 scholarships, will be drawn Aug. 6.

Enter or learn more at shotatamillion.com or call 1-877-356-1511. 

Contributing: Associated Press, The Courier and Daily Comet. 

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.