NEW YORK (AP) — U.S. health officials on Friday again urged people to stop vaping until they figure out why some are coming down with serious breathing illnesses.

Officials have identified about 450 possible cases, including as many as five deaths, in 33 states. The count includes newly reported deaths in California, Indiana and Minnesota.

No single vaping device, liquid or ingredient has been tied to all the illnesses, officials said. Many of the sickened — but not all — were people who said they had been vaping THC, the chemical that gives marijuana its high. Many are teens.

Health officials...