Ford Motor Co said on Tuesday it has ordered a dozen ultra-cold freezers that can safely store Pfizer Inc's COVID-19 vaccine, a move aimed at ensuring the U.S. automaker's workers have access to vaccines when they are rolled out nationally.

Ford's purchase mirrors efforts by U.S. states and cities to buy equipment to store millions of doses of Pfizer's vaccine at temperatures of minus 70 Celsius (minus 94 Fahrenheit), significantly below the standard for vaccines of 2-8 C (36-46 F).

Health care providers and states are preparing for a new type of vaccines by Pfizer and Moderna Inc that require lower temperatures for storage.

"We're doing this so that we can make the vaccine available to our employees on a voluntary basis," Ford spokeswoman Kelli Felker said.

Details of how Ford will use the freezers, which are expected to be delivered by year end, are still being worked out, she said.

Assembly workers are considered essential in most states, but not at the top of the list for vaccines, which are expected to be distributed first to healthcare workers and nursing home residents.

Automakers have been largely able to avoid spread of the virus among hourly workers in their assembly plants after a two-month shutdown earlier in the year, but COVID-19 cases and hospitalizations are spiking in the United States, especially in the Midwest.

Felker did not know which company is supplying Ford with the freezers. Major manufacturers include Thermo Fisher Scientific Inc, PHC Corp of North America, Luxembourg's B Medical Systems, Stirling Ultracold and Helmer Scientific.

Some specialty freezer makers have warned of months-long waits for units.

Ford, which decided to buy the freezers on its own and is not working with other companies or states, did not disclose how much it spent, but the specialized freezers required by Pfizer's vaccine can cost $5,000 to $15,000 apiece, according to industry officials.