The source is familiar with the operation, according to ABC.
The Federal Aviation Administration had already given the OK for the first mass air shipment of a COVID-19 vaccine.
The FAA said it established a transport team in October to "ensure safe, expeditious and efficient transportation of vaccines."
The agency said it is also ensuring around-the-clock air traffic services in an effort to prioritize flights carrying vaccines and personnel.
DHL will also be involved in the transportation and storage of the vaccine in various locations, a spokesman said Saturday. The delivery service would not disclose exactly where the COVID-19 vaccine would be stored.
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"At the same time, our DHL Global Forwarding division has a major life science and healthcare certified facility at Chicago O'Hare which will play an important role in our activities to support the vaccine logistics," the spokesman said.
On Friday, a United spokesperson said, "United Cargo established a COVID Readiness Task Team earlier this summer to help ensure we have the right people, products, services, and partnerships in place to support a vaccine distribution effort on a global scale. We have made a commitment to our pharmaceutical and medical customers that we are ready to safely and effectively support their vaccine transportation needs. The safety and security of these commodities is our priority and we are proud to be a trusted partner in these efforts."