WASHINGTON (AP) — U.S. health officials have authorized a plan to stretch the nation’s limited supply of monkeypox vaccine by giving people just one-fifth the usual dose. In an announcement issued Tuesday, they cited research suggesting that the reduced amount is about as effective. The so-called dose-sparing approach also calls for administering the Jynneos vaccine with an injection just under the skin rather than into deeper tissue — a practice that may rev up the immune system better. The highly unusual step is a stark acknowledgment that the U.S. currently lacks the supplies needed to vaccinate everyone seeking protection from the rapidly spreading virus.