UPS and FedEx usually compete fiercely for business. Now, the rivals are working closely together to ship the coronavirus vaccine developed by Pfizer and BioNTech, the first of the vaccines to win U.S. government approval.

At a news conference Saturday, Gen. Gustave Perna, chief operating officer of Operation Warp Speed, the federal effort to bring a vaccine to market, said that boxes were being packed at Pfizer’s plant in Kalamazoo, Michigan, and would be shipped to UPS and FedEx distribution hubs, where they would be dispersed to 636 locations across the country. Pfizer said shipping would start early Sunday morning.

Perna specified that 145 sites would receive the vaccine on Monday, 425 on Tuesday and 66 on Wednesday.

“Make no mistake, distribution has begun,” he said. UPS said it expected to start transporting the vaccine on Sunday morning, when employees stationed at Pfizer’s facility in Michigan will affix special Bluetooth- and radio-enabled tracking tags to each shipment. An aircraft waiting nearby will take the vaccine to the company’s Worldport air cargo hub in Louisville, Kentucky, a sprawling 5.2 million-square-foot sorting facility. Future shipments of the vaccine will also be transported by truck to the Louisville hub, which is up to a 6-hour drive from Michigan.

“This is the moment we’ve been waiting for,” Wes Wheeler, president of the company’s health care division, said in an interview Saturday. “We’ve been planning for months with daily calls, drilling down to really quite minute details.”

Wheeler said he planned to oversee the first vaccine shipments from a newly established 24/7 command centre in Louisville, which will be staffed at any given time by teams of five to 10 people who will monitor each vaccine package as it moves through UPS’ network.