What does “the jury is still out” mean?

The jury is still out means a question has no clear answer yet. The picture comes from a courtroom: while the jury is “out” of the room, still discussing, there is no verdict. So when the doctor says “the jury’s still out on is vaping worse or less risky than cigarettes,” he means the experts have not decided — the evidence is not complete.

American newspapers used the phrase literally as far back as the 1800s (“The jury are still out”); the figurative use came about a century later. In the interview, the doctor also explains why the jury is still out: vapes only appeared in the US around 2010, and with cigarettes the real health damage took decades to become visible. Expect this idiom in almost any news debate about science or health.