FedEx will use Boeing 767 aircraft, like the one pictured here, to deliver COVID-19 vaccines.

Air cargo is vital to our lives. Planes swiftly deliver our food and mail, goods we buy online (like the laptop I'm writing this on) and flowers we order for Mother's Day. Approximately 35% of world trade travels in airplanes, according to the International Air Transport Association, accounting for $6 trillion worth of goods.

It's also critical to public health. Air cargo carriers will be at the forefront of distributing the Pfizer and Moderna COVID-19 vaccines around the planet. Transporting vaccines by air isn't new -- that's how flu vaccines get distributed every year -- but the significance and scope of the COVID-19 vaccine distribution is unmatched. Pfizer alone expects to produce up to 50 million vaccine doses in 2020 and 1.3 billion in 2021, and they'll all need to get somewhere.

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Familiar giants like UPS, DHL and FedEx will play a big role in the process, but so will passenger airlines with cargo operations, like American, United and Delta. Here's what they're doing to prepare to keep the vaccines safe and carry them to you.

Just keep in mind that even though vaccines are now being administered, the coronavirus pandemic is raging on, with almost 74 million cases and 1.65 million deaths around the world to date. Social distancing and mask wearing are still absolutely essential for fighting the spread of the virus and protecting the health of you and others. And they'll remain that way for many months, even after you're vaccinated.

Pfizer's vaccine, just approved for use by the FDA on Friday, needs to be stored at a temperature of minus 94 degrees Fahrenheit (minus 70 degrees Celsius). Cargo that must be kept extremely cold typically can be transported in "active" containers with built-in temperature controls (like a portable freezer) or "passive" containers that are cooled with dry ice. Either way, all containers used to ship the vaccines will have temperature recorders to ensure vaccine safety.

The advantage of passive containers is that they're lighter, making them more portable, and they don't require a power source. Intending to distribute its vaccine as fast as possible, Pfizer went with the passive option by designing its own containers (according to The Wall Street Journal, the containers are the size of a suitcase).

Airlines have more options for vaccines that don't need to be kept as cold, likeModerna's(which still needs FDA approval). United Airlines, for example, says that with 15 different cargo container options, "we can support a variety of temperature needs whether ambient, cool or frozen."

Delta employees offload vaccines from an aircraft.

UPS says it will monitor all shipments from a new dedicated command center. The facility will be staffed around the clock and will collect data from the temperature recorders in shipping containers. Each UPS package also will have a tag identifying it as a vaccine shipment. The company built its own dry ice manufacturing facility at its hub in Louisville, Kentucky, with a capacity of more than 24,000 pounds each day.

Other carriers will monitor shipments as well. American Airlines will do so from its Cargo Control Center at its headquarters in Fort Worth, Texas, and Delta Airlines will have a "Vaccine Control Tower" with centralized monitoring and customer reporting.

Cargo containers are loaded into a United Airlines Boeing 777 at San Francisco International Airport in 2018.

It depends on the carrier and the available aircraft it has in its fleet. But generally a bigger plane is better, since it can fit more shipments. United Airlines says one of its Boeing 777-200s, one of the largest aircraft in its fleet, has the ability to carry more than a million doses of vaccine. American also operates the 777, while Delta's largest airliner is the comparatively sizedAirbus A350.

With largely wide-body fleets includingBoeing's 777, 767 and 747; the Airbus A300; and the McDonnell Douglas MD-11, FedEx and UPS will be able to move large quantities of doses as well.

Now playing: Watch this: How United Airlines prepares a Boeing 777 between flights

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Yes. Though it depends on the route flown, United and American will use both all-cargo and passenger flights. The vaccines will be stored below the passenger cabin in the cargo hold.

A FedEx employee handles dry ice for a shipment.

Dry ice is solid carbon dioxide, the same molecule humans and animals breathe out. As long as it's handled properly, it'll keep everything from food to medicines cold for long periods without posing much of a health risk (that is, unless you touch it with bare hands).

The bigger danger is if dry ice warms above minus 78.5 degrees Celsius ( minus 109.3 degrees Fahrenheit). At that point it will sublimate, meaning it turns directly to an odorless and colorless gas, skipping the liquid state. Carbon dioxide is harmful when we breathe it in. A small amount can cause a loss of cognitive function, fatigue or unconsciousness (not ideal conditions for a pilot), and too much can lead to a coma or even asphyxiation.

Because those dangers are compounded in an enclosed space like an airplane, the Federal Aviation Administration on Dec. 10 issued a Safety Alert for Operators advising carriers to do the following (among other things):

American monitors flights from its operations control center in Fort Worth, Texas.

Given that the FAA manages the nation's air traffic control system, it'll have a big role. In an email to CNET, an agency spokeswoman said this:

"The FAA will handle flights carrying COVID-19 vaccines the same way we handled flights carrying personal protective equipment in the spring of 2020. Airlines will provide lists of flights carrying COVID-19 vaccines to the FAA's Command Center, which will alert air traffic facilities in the field that these are priority flights. The Command Center will closely track the flights along their routes to ensure they are given priority to the degree possible."

The FAA also issued an advisory for airports handling vaccine flights, with points like giving priority access to ground vehicles collecting the vaccine, and it relaxed rules on how much dry ice airlines can carry on their flights. (Even passengers can carry a small amount in checked baggage.) United said it can now carry 15,000 pounds of dry ice per flight -- five times more than normally permitted, and FedEx will be able to transport approximately 500,000 dry ice shipments a month.

Vaccines ready for shipment at a UPS facility.

Once a vaccine shipment arrives at an outbound shipping facility, airlines will need to keep it cold. This temperature-controlled cargo infrastructure already exists, though some companies will be expanding their network to meet demand.

FedEx says it's added more than 10 secure cold storage facilities over the past three years and now has more than 90 in North and South Americas, Asia, Australia and Europe. The company also added ultracold freezers, and expanded freezer and refrigerator capacity at some locations.

UPS has invested in a "freezer farm" in Louisville for ultracold storage and will supply portable freezers for vaccine dosing sites where dry ice isn't available.

American will use its existing temperature-controlled facilities at airports in Philadelphia, Miami, Dallas, London, Chicago and San Juan, Puerto Rico. Delta will rely on cold storage at airports in Atlanta, Detroit, Los Angeles, New York and Seattle.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.

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COVID-19 vaccine is flying high and on dry ice to reach you - CNET