NEW YORK—Many U.S. holiday shoppers, wary of spending time in stores during the latest surge of COVID-19 cases and nervous about packages not arriving before Christmas, were on a mission on Saturday: snatch up last-minute gifts fast or pick up online purchases in-store. The “Super Saturday” before Christmas is traditionally the busiest day of the year for holiday purchases, and this year online retail has been extra busy. But news reports about high-priority vaccine shipments have many Americans fretting that gift deliveries could be delayed this week. “If you haven’t ventured out and you haven’t gotten your gifts, you almost have to,” said Marshal Cohen, chief retail industry adviser at NPD Group. “Online orders aren’t going to get delivered on time and nobody wants to risk showing up empty handed.” U.S. retailers are expected to ring in record sales, with over 150 million American shoppers slated to buy holiday gifts …