Moderna's vaccine has a significant advantage over Pfizer's

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(CNN) - Moderna announced this morning that its coronavirus vaccine is 94.5% effective against the virus, making it the second vaccine in the United States to have a stunningly high success rate.

RELATED: Moderna's coronavirus vaccine is 94.5% effective, according to company data

Last week, Pfizer announced that early data show its vaccine is more than 90% effective against the disease.

RELATED: Pfizer says early analysis shows its COVID-19 vaccine is 90% effective

While the two vaccines appear to have very similar safety and efficacy profiles, Moderna's vaccine has a significant practical advantage over Pfizer's.

Pfizer's vaccine has to be kept at minus 75 degrees Celsius — or about minus 103 degrees Fahrenheit. No other vaccine in the US needs to be kept that cold, and doctors' offices and pharmacies do not have freezers that go that low.

Moderna's vaccine can be kept at minus 20 degrees Celsius, which is about minus 68 agrees Fahrenheit. Other vaccines, such as the one against chickenpox, need to be kept at that temperature.

That means Moderna's vaccine can be kept in "a readily available freezer that is available in most doctors' offices and pharmacies," said Dr. Tal Zacks, Moderna's chief medical officer. "We leverage infrastructure that already exists for other marketed vaccines."

Another advantage of Moderna's vaccine is that it can be kept for 30 days in the refrigerator, the company announced Monday. Pfizer's vaccine can last only five days in the refrigerator.

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