Rival US companies UPS and FedEx are working side-by-side to ship the Pfizer-BioNTech Covid-19 vaccine, after it was approved for emergency use by the US Food and Drug Administration (FDA) on Friday.

The two shipping companies said that they had put plans, which they had been working for months, into action after the coronavirus vaccine received emergency use authorisation, reported The New York Times. During a news conference on Saturday, General Gustave F Perna, the chief operating officer of Operation Warp Speed, the federal effort to bring a market, said that the boxes were being packed at Pfizer's plant in Michigan, and would be shipped to UPS and FedEx distribution hubs, where they would be dispersed to 636 locations around the country.

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

UPS said that the company expects to start transporting the Covid-19 vaccine as soon as Sunday morning when employees stationed at Pfizer's facility in Michigan will affix special Bluetooth- and radio-enabled tracking tags to each shipment, reported The New York Times.

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

"You have two fierce rivals here, and competitors, in FedEx and UPS, who literally are teaming up to get this delivered," said Richard Smith, a FedEx executive, to the Senate's Subcommittee on Transportation and Safety on Thursday.

Both companies said the shipments would be closely tracked and monitored, and would be given priority over other packages. To ship its vaccine, Pfizer designed specialized containers packed with enough dry ice to keep a minimum of 975 doses cool for up to 10 days. Each comes with a tracking device, according to The New York Times.

This comes after the FDA authorized Pfizer's Covid-19 vaccine for emergency use on Friday for the prevention of coronavirus disease in individuals 16 years of age and older.

"The FDA's authorization for emergency use of the first Covid-19 vaccine is a significant milestone in battling this devastating pandemic that has affected so many families in the United States and around the world," said FDA Commissioner Stephen M. Hahn, MD.

The Pfizer-BioNTech Covid-19 vaccine was first approved in the United Kingdom, then in countries Canada, United States and Mexico.