WASHINGTON (AP) – Pfizer on Tuesday asked the U.S. to authorize extra-low doses of its COVID-19 vaccine for children under 5, potentially opening the way for the very youngest Americans to start receiving shots as early as March. IN AN EXTRODINARY MOVE, the FOOD AND DRUG ADMINISTRATION HAD URGED PFIZER AND ITS PARTNER BIONTECH TO APPLY EARLIER THAN THE COMPANIES HAD PLANNED. The nation’s 19 million children under 5 are the only group not yet eligible for vaccination against the coronavirus. Many parents have been pushing for an expansion of shots to toddlers and preschoolers, especially as the omicron wave...