The Food and Drug Administration has cleared Moderna and Pfizer’s COVID booster shots for all Americans over the age of 18. The extension of the existing emergency use authorizations to include younger adults was announced in statements from the two drug makers Friday morning. The boosters were previously authorized for anyone 65 or over who had been vaccinated with the Pfizer or Moderna vaccines at least six months ago, as well as some vulnerable adults under 65. Stéphane Bancel, chief executive of Moderna, said: “This emergency use authorization comes at a critical time as we enter the winter months and face increasing COVID-19 case counts and hospitalizations across the country.” Albert Bourla, Pfizer’s CEO, said: “With boosters, more adults will now have the opportunity to help preserve a high level of protection against this disease.” Several states pre-empted the FDA’s approval and had already opened up boosters for all adults in the past week.