Health and Human Services Secretary Alex Azar said the complexity associated with Pfizer’s coronavirus vaccine is not the sub-freezing storage requirements, but instead the large volume of 975 doses per package.

Azar told reporters on a call Monday that the media frequently questions Pfizer’s coronavirus vaccine’s ultra-low cold chain. The vaccine must be stored at temperatures of minus 70 degrees Celsius (minus 94 F) or below.

To handle that issue, and others that might arise during transportation, Pfizer has specially designed temperature-controlled thermal shippers using dry ice to maintain that temperature. Also, the containers will use GPS-enabled thermal sensors with control towers to track the location and temperature of each vaccine shipment.

Dry ice is poured into a box containing the Pfizer-BioNTech COVID-19 vaccine as it is prepared to be shipped at the Pfizer Global Supply Kalamazoo manufacturing plant in Portage, Mich., Sunday, Dec. 13, 2020. (AP Photo/Morry Gash, Pool)

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However, Azar said Pfizer’s 975-dose packaging poses the real obstacle. He went so far as to call the sub-freezing hurdles a "misconception."

“One misconception I get asked about a lot by the media with the Pfizer vaccine and the ultra-low cold chain around that," he said.

A Pfizer spokesperson previously addressed the vaccine's cold temperature storage requirements in an emailed statement to Fox News: “Our distribution is built on a flexible just-in-time system, which will ship the frozen vials to the point of vaccination."

Boxes containing the Pfizer-BioNTech COVID-19 vaccine are moved to the loading dock for shipping at the Pfizer Global Supply Kalamazoo manufacturing plant in Portage, Mich., Sunday, Dec. 13, 2020. (AP Photo/Morry Gash, Pool)

Earlier reports cited concerns over the logistical challenge imposed on both sophisticated and rural hospitals, and developing countries' lack of necessary equipment to handle the sub-freezing requirements. BUt Azar told reporters that the vaccine could be shipped to rural areas. 

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The vaccine is delivered on dry ice and remains stable for about five days. Azar said the Moderna vaccine, which is still pending FDA emergency approval, “will be more flexible, [in a] smaller package, also a regular freezer for storage capabilities.”

“There’s nothing in the nature of the Pfizer vaccine or distribution that prevents use ... just want to make sure you use all those doses within the relevant time frame,” he said.

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Fox News' Peter Aitken contributed to this report.