The coronavirus vaccine rollout in the United States might be about to get much less complicated. Drugmaker Johnson & Johnson has asked the U.S. Food and Drug Administration to approve its vaccine—the first one in the world to only require one shot, rather than a double dose. If approved, it would massively boost vaccine supply and take away part of the huge logistical challenge of injecting every person twice. It can also be stored in a standard refrigerator, rather than in ultra-cold storage like some other vaccines. J&J’s request comes after it published a report last week in which it said the vaccine had a 66 percent rate of preventing infections—lower than the approved double-shot vaccines, but still high enough to be considered effective. The U.S. has already agreed to pay $1 billion for 100 million doses of the J&J shot, and has the option to buy 200 million more.