WASHINGTON (AP) — The U.S. booster campaign is getting a lot simpler now that regulators have opened extra vaccine shots to all adults. The Food and Drug Administration’s Dr. Peter Marks says the new approach will streamline booster decisions as COVID-19 cases begin rising again across the country. The action follows months of pressure from the Biden administration to broaden booster use. But the FDA also faced pushback from other experts who questioned whether most young, healthy adults need extra doses. Marks spoke to The Associated Press about how the FDA made its decision.