With the final lottery drawing winner expected to be announced Thursday, you might be asking how successful the "Shot of a Lifetime" was in getting more people vaccinated.
Gov. Jay Inslee said earlier this month the lottery has led to a 24% increase in vaccination rates across Washington.
Inslee said the Institute for Disease Modeling estimated the lottery has so far led nearly 30,000 additional people to get vaccinated against the coronavirus.
Across the U.S., lotteries have seen mixed results. Some states that implemented lotteries have reported boosts in vaccinations. But Ohio, the first state to offer a lottery, saw an early spike slow and has ended the program.
"The "Shot of a Lifetime" is working & more people are getting vaccinated," Inslee said on Twitter.
So, how did the state figure that out? 30,000 does not represent a 24% increase in the total number of residents vaccinated. Instead, it is the based on the comparison of the number of people who were expected to get vaccines during this period of falling vaccination rates and the number who actually ended up getting shots.
Franji Mayes, an emergency communications consultant for the health department, explained how the state got its numbers.
To estimate the effect of the "Shot of a Lifetime" promotion on vaccination rates, the state started by looking at the daily percentage of unvaccinated people who received their first shot by age group, since vaccine eligibility and trends differ by age group.
In general, they had seen that once an age group becomes eligible for the vaccine, vaccination rates increase rapidly, hit a peak, then decline steeply. By the end of May, right before the lottery was announced, vaccination rates for people getting their first dose were decreasing on average by about 3 to 10% each day, Mayes said.
In particular, younger age groups were seeing higher rates of decline.
After the announcement, the state saw an increase in vaccination rates across younger age groups, vaccination rates holding steady in middle age groups and decreased rates of decline in older age groups, she said.
"Since rates were already declining fast before the announcement and we expected those declines to continue, we wouldn't necessarily see the impact of the lottery if we just look for an increase in overall vaccination rates," she said. "To understand the likely impact, we need to estimate the vaccination rates we would have expected to see if the lottery hadn't happened and compare them with the rates we actually saw."
When they compared the rates projected for each age group without the lottery to the rates seen once the lottery was implemented, they found:
* The largest difference between the expected rates and actual rates occurred in those under 18, where actual rates increased and pre-lottery trends were decreasing the fastest.
* The differences between the expected rates and actual rates were progressively smaller for older age groups, with minimal difference in the oldest age groups.
"Then, to get an idea of the overall effect of the lottery, we put together the estimates for how many additional people 16 and older got their first shot," she said. "Our best estimate is that between June 3 and June 22, about 28,500 more people got their first shot than we would have expected without the lottery — a 24% increase."
At the beginning of June, Inslee announced that the state would give out more than $2 million in prizes to vaccinated Washingtonians, to incentivize the shots.
So far, four $250,000 prize winners have been chosen: Dillon T., Lance R., nursing student Marissa P. and Stephen T.
The cash prizes are the largest awards in an incentive package that also includes tuition money for students, tickets for air travel and sporting events, and other prizes.
The winner of the largest drawing of $1 million was drawn on Tuesday, and is expected to be announced Thursday. A separate lottery for residents who were vaccinated through Veterans Affairs or the Department of Defense will be drawn on July 20.
