The gulf nation joins a list of countries -- including the U.K., U.S., Canada, Bahrain, Saudi Arabia and Mexico -- that have authorized the emergency use of the Pfizer/BioNTech COVID-19 vaccine.

-ABC News' Christine Theodorou

With Sunday's vaccine shipment now in transit, Pfizer has began preparations to ship out an additional 400 boxes of the vaccine on Monday.

There are 975 vials per box -- each vial provides five doses of the COVID-19 vaccine, the company said.

There are 195 vials per tray and 60,000 vials per freezer.

The first vaccines in the U.S. have now left the Pfizer facility and are on their way to all 50 states.

Two main trucks left on Sunday morning -- an additional truck will come in later to pick up a few boxes and take them to the U.S. territories.

On Monday Pfizer has an order for another 400 boxes of the vaccine as well as an order for a slightly less amount of boxes on Tuesday, the company said.

The first shipments are expected to arrive at 145 sites on Monday, 425 sites on Tuesday and another 66 sites on Wednesday, Gen. Gus Perna of the Trump administration's Operation Warp Speed vaccine program said.

At those sites, the vaccines will be paired with ancillary kits to assist with the vaccinations. The kits contain needles, syringes, alcohol swabs, diluent, safety gear and vaccine reminder cards.

-ABC News' Joshua Hoyos and Luis Martinez

FedEx has begun its shipment process of the Pfizer vaccine in the U.S. on Sunday morning, the company posted on Twitter.

U.S. President-elect Joe Biden on Monday announced key nominations and appointments of his health team, a slate of experts and public officials who will lead his administration's response to the coronavirus pandemic.

"This trusted and accomplished team of leaders will bring the highest level of integrity, scientific rigor and crisis-management experience to one of the toughest challenges America has ever faced -- getting the pandemic under control so that the American people can get back to work, back to their lives and back to their loved ones," Biden said in a statement. "This team of world-class medical experts and public servants will be ready on day one to mobilize every resource of the federal government to expand testing and masking, oversee the safe, equitable and free distribution of treatments and vaccines, reopen schools and businesses safely, lower prescription drug and other health costs and expand affordable health care to all Americans, and rally the country and restore the belief that there is nothing beyond America's capacity if we do it together."

California Attorney General Xavier Beccera is nominated to serve as the Secretary of Health and Human Services.

Dr. Vivek Muthy, a physician and research scientist, is nominated to be the Surgeon General, a role he served during the Obama administration.

Dr. Rochelle Walensky, an expert on virus testing, prevention and treatment, is nominated to serve as director of the Centers for Disease Control and Prevention.

Dr. Marcella Nunez-Smith, an expert on health care disparities, will serve as the COVID-19 Equity Task Force Chair.

As Biden said last week, Dr. Anthony Fauci will stay on in his current role as director of the National Institute of Allergy and Infectious Diseases. Fauci will also serve as Biden's chief medical adviser on COVID-19.

Jeff Zients, co-chair of Biden's transition team who led the Obama administration's National Economic Council, will serve as coordinator of the COVID-19 Response as well as counselor to the president.

Natalie Quillian, a national security expert, will serve as deputy coordinator of the COVID-19 response.

ABC News' John Verhovek contributed to this report.