A syringe is prepared with the Pfizer COVID-19 vaccine at a clinic in the Norristown Public Health Center in Norristown, Pa., on Tuesday, Dec. 7, 2021. Amid concern about vaccines protecting against delta and omicron variants that are spreading, the push to get coronavirus booster shots is not an immediate priority in most of the top sports leagues in North America. AP Photo/Matt Rourke, File)