Former president Donald Trump was booed by some of his supporters at a rally in Cullman, Alabama on Saturday after he encouraged them to get vaccinated against COVID-19.

“You know what? I believe totally in your freedoms, I do. You gotta do what you have to do. But I recommend taking the vaccine! I did it. It’s good. Take the vaccines,” Trump said, evoking boos from the crowd. “No, that’s okay, that’s all right, you’ve got your freedoms. But I happened to take the vaccine.”

“If it doesn’t work, you’ll be the first to know,” Trump joked. “But it is working. You do have your freedoms, you have to maintain that.”

Trump’s remarks arrive as Alabama reaches the second-lowest vaccination rate in the U.S. According to data from the Centers of Disease Control and Prevention, just 47 percent of the total state population has received at least one dose of the coronavirus vaccine. Meanwhile, only 35 percent of Alabamians are fully vaccinated, which is the lowest rate in the nation.

Amid the state’s low vaccination rates, Alabama’s public health officials are urging people to re-consider getting the vaccine. 

“How much more information do we need to say that we can do this in Alabama?” Dr. Karen Landers, Assistant State Health Officer for the Alabama Department of Public Health, asked reporters last month. “We have vaccine that is readily available, it’s free, it’s safe, it can be given at any time. What else can we do? We’ve done everything we need to do, and these trends are not looking good. We could be in a really bad spot within a couple of weeks.”