US regulators, experts take up thorny vaccine study issues

WASHINGTON (AP) — The U.S. regulators who will decide the fate of COVID-19 vaccines are asking outside scientists if their standards are high enough. The Food and Drug Administration may have to decide by year’s end whether to allow use of the first vaccines. A federal advisory committee is debating Thursday whether the guidelines FDA has set for vaccine developers are rigorous enough. Among the big questions: Exactly how much evidence is needed to be sure a vaccine is safe and effec