How much must the shots rev up someone’s immune system to really work? And could revving it the wrong way cause harm?

Even as companies recruit tens of thousands of people for larger coronavirus vaccine studies this summer, behind the scenes, scientists are still testing ferrets, monkeys and other animals in hopes of clues to those basic questions.

“We are in essence doing a great experiment,” said Ralph Baric, a coronavirus expert at the University of North Carolina, US, whose lab is testing several vaccine candidates in animals.

With animals, “we’re able to perform autopsies and look specifically at their lung tissue and get a really deep dive in looking at how their lungs have reacted,” Kate Broderick, research chief at Inovio Pharmaceuticals, said.

Read the full AP story here.