KALAMAZOO, Michigan (NBC News/KXAN) — The first shipments of Pfizer’s COVID-19 vaccine are being loaded up and moved out.

Early Sunday morning, workers at Pfizer’s Michigan headquarters started packing up the long awaited COVID-19 vaccine.

The vials are initially stored in the freezer area where the vaccine is kept at temperatures hovering around negative 94 degrees Fahrenheit or negative 70 degrees Celsius.

Workers started rolling bins and moving vaccines from the freezer farm into coolers packed with dry ice.

From there, the vials are moved on to a belt and packed with more dry ice until it’s moved out to the loading dock.

Workers paused for a moment and started to clap as the first boxes of vaccine were being moved to a loading dock.

The trucks outside the plant will head to Fed-Ex and UPS hubs around the country to be delivered to 636 pre-determined locations nationwide. 145 of those sites should receive the vaccine by Monday with other sites getting the vaccine by Wednesday.

Pfizer — the maker of the vaccine — has confirmed to NBC News that all 50 states will receive some portion of the first round of shipments.

The Food and Drug Administration authorized the use of Pfizer’s COVID-19 vaccine late last Friday night. An estimated 2.9 million doses will be distributed within a week.

That number will ramp up to as many as 40 million doses by the end of the year. In addition to the Kalamazoo location, Pfizer is currently using two other manufacturing sites to produce the vaccine.

Pfizer and its partner BioNTech say based on current projections, they believe they could potentially supply up to 1.3 billion doses by the end of next year.

The company says it supplied vaccine to over 150 clinical trial sites around the world, reaching about 44,000 participants.