Amazon gave away cars and $100,000 cash bonuses to a handful of vaccinated warehouse workers as part of its running sweepstakes to encourage employees to get inoculated.

Amazon Vest Life, which provides news, lifestyle, and information for employees at the front lines, announced Monday that four workers from Whole Foods and another Whole Foods employee received cars valued as high as $40,000 each.

Last week, three warehouse and Whole Foods employees were given $100,000 cash awards for getting vaccinated, Amazon said in a separate Instagram post.

Amazon launched an August sweepstakes in order to recognize employees who had received the Covid-19 vaccine, and to encourage those still unvaccinated to enter. Called “Max Your Vax,” it offers employees the chance to win cars, a week of paid time off complete with a $12,000 vacation package, as well as cash awards worth $100,000 and $500,000.

Amazon says that there will be 18 prizes awarded from mid-October to the end of this month. Amazon requires employees to show proof of their full vaccination via an internal website.

Amazon does not require employees to become vaccinated. But these sweepstakes can be used as an incentive to encourage vaccination. Amazon offers new employees bonuses as high as $100 and to existing employees who can show proof of vaccines.

Amazon wants its frontline employees to be vaccinated, as Covid delta is spreading rapidly around the world. The company has resumed some coronavirus safety measures that were previously in place, including mask mandates in U.S. warehouses. Additionally, Amazon is working to restart its coronavirus testing program in its warehouses after winding down its on-site testing facilities, the Seattle Times reported.

Amazon representatives didn’t respond immediately to our request for comment.