LOUISVILLE, Ky. — Pfizer's COVID-19 vaccine has arrived in Louisville today as UPS prepares to ship thousands of doses nationwide.

The first vaccine shipment will move through Louisville's UPS Worldport on Sunday, according to UPS Public Relations Manager Jim Mayer. Some will be designated for use in Kentucky but most are being distributed across the country.

The 757 touched down with the Pfizer-BioNTech COVID-19 vaccine at Muhammad Ali International Airport shortly after noon.

Houston Mills, UPS’s vice president of Flight Operations, was the captain.

"The gravity of what this vaccine will mean to so many people, I think, is what makes it so powerful, and so to be part of this moment, knowing that this vaccine is going to bring hope and a change, and, I know, if I’m like anyone else out there we’ve got COVID fatigue, you know, we are ready to move on beyond COVID so I think the gravity of this vaccine and the hope that it brings is what makes this a special moment," Mills said.

Mills said he previously flew for the U.S. Marine Corps, and called Sunday's flight a different type of mission.

"To finally have a solution out here that’s literally going to help people and save lives it’s just very humbling," he said.

Shipments of the Pfizer vaccine will set in motion the biggest vaccination effort in American history at a critical juncture of the pandemic that has killed 1.6 million and sickened 71 million worldwide.

Initially, about 3 million doses were expected to be sent out, and the priority is health care workers and nursing home residents as infections, hospitalizations and deaths soar in the U.S. With numbers likely to get worse over the holidays, the vaccine is offering a bright spot in the fight against the pandemic that’s killed nearly 300,000 Americans.

Federal officials say the first shipments of Pfizer’s vaccine will be staggered, arriving in 145 distribution centers Monday, with an additional 425 sites getting shipments Tuesday, and the remaining 66 on Wednesday. The vaccine, co-developed by German partner BioNTech, is being doled out based on each state’s adult population.

UPS CEO Carol Tomé said the company is fully equipped to assist with the crucial chain of distribution.

“Vaccine distribution is a key part of moving our world forward by delivering what matters,” says Carol Tomé, CEO of UPS. “We have dedicated and hardworking people around the world who have been trained to store, handle, transport and deliver vaccines. We’re pleased to support our healthcare partners with smart, efficient logistics for these vaccines that will protect communities and save lives.”

The vaccine is heading to hospitals and other sites that can store it at extremely low temperatures — about 94 degrees below zero. Pfizer is using containers with dry ice and GPS-enabled sensors to ensure each shipment stays colder than the weather in Antarctica.

Doses should be delivered to all vaccination sites identified by states, such as local pharmacies, within three weeks, federal officials said.

While the vaccine was determined to be safe, regulators in the U.K. are investigating several severe allergic reactions. The FDA’s instructions tell providers not give it to those with a known history of severe allergic reactions to any of its ingredients.

Another vaccine by Moderna will be reviewed by an expert panel this week and soon afterward could be allowed for public use.

Bryce Shreve is a digital producer with Spectrum News 1 KY. He is a recent graduate of Indiana University Southeast and joined the staff in November, 2020.

Spectrum News 1 reporter Eileen Street produced the video component of this story.