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How Does Moderna's Vaccine Measure Up To Pfizer's?

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Key Takeaways

  • Biotechnology company Moderna says its COVID-19 vaccine candidate is 94.5% effective.
  • The vaccine joins Pfizer and BioNTech as a promising contender in developing a vaccine to thwart the spread of COVID-19.
  • Moderna’s vaccine is stored at a warmer temperature than Pfizer and BionNTech's vaccine, making distribution easier.


On Monday, biotechnology company Moderna reported the results of a Phase 3 vaccine trial against coronavirus. Moderna said its vaccine is 94.5% effective.

The news comes on the heels of a similar announcement from Pfizer and BioNTech on November 9 that the companies had partnered to developed a 90% effective vaccine. The effectiveness was updated to 95% on Wednesday after Phase 3 trial data was finalized.

“Both the Moderna and Pfizer vaccines have had remarkable efficacy in early results from Phase 3 trials,” Don L. Goldenberg, MD, professor in the Departments of Medicine and Nursing at Oregon Health & Science University and author of How the COVID-19 Pandemic Is Affecting You and Your Healthcare, tells Verywell. “The initial results from the Moderna study did include vaccine efficacy in high-risk people, either from age or underlying disease."

He added: “Both vaccines use the same technology and thus far have been free of alarming adverse side effects.”

While the more COVID-19 vaccines developed, the merrier, you may be wondering how the vaccine candidates differ from one another.

Results Are Based On a Diverse Pool of Volunteers

Moderna noted in its news release that the study, known as the COVE study, enrolled more than 30,000 participants across the United States. Sixty-three percent of the participants are White, 20% are Hispanic; 10% are Black; and 4% are Asian Americans, according to Moderna’s demographic information. Twenty-five percent of the volunteers are 65 or older.

On the other hand, the 44,000 participants in the Pfizer study are from six different countries: the United States, Germany, Turkey, South Africa, Brazil, and Argentina. “Approximately 42% of global participants and 30% of U.S. participants have racially and ethnically diverse backgrounds, and 41% of global and 45% of U.S. participants are 56 to 85 years of age,” the company noted in a news release. Half of the participants received the vaccine, while the other half were given a placebo.

Pfizer announced on November 18 that its vaccine presents no serious side effects. 

Stewart Coffman, MD, MBA, FACEP

“Hopefully, by the end of this year, we will have millions of doses of both vaccines we can begin to distribute. Vaccines are critical public health measures to protect the health and safety of communities and slow the spread of this virus.”

— Stewart Coffman, MD, MBA, FACEP

The Vaccines Are Stored Differently

While vaccine storage may be something you've never thought about, the temperature at which they are stored is extremely important, says Stewart Coffman, MD, MBA, FACEP, senior vice president at Envision Healthcare.

“It is critical that a vaccine is stored at the appropriate temperature,” Coffman tells Verywell. “Each of these vaccines will be distributed with detailed guidance on how they are to be administered, because if stored at an inappropriate temperature, it will become deactivated and less effective at preventing the spread of COVID-19.” 

For Pfizer, that will require storing the vaccine at -70°C (-94° F). Moderna will be shipped at -20°C (-4°F), equal to most home or medical freezer temperatures, and have a shelf life of up to 6 months at that temperature. Moderna’s shelf life is considered to be one of the vaccine’s benefits; once thawed, it can remain stable at standard refrigerated conditions of 2° to 8°C (36° to 46°F) for up to 30 days within the 6-month shelf life. 

“The stability at refrigerated conditions allows for storage at most pharmacies, hospitals, or physicians’ offices,” the company noted in a news release. 

When Will We See a Vaccine? 

Even though the results are promising for both the Pfizer and Moderna vaccines, widespread distribution of the vaccines will first require approval by the U.S. Food and Drug Administration (FDA). Once that occurs, Pfizer and BioNTech said they expect to produce up to 50 million vaccine doses globally in 2020 and up to 1.3 billion doses by the end of 2021.

Moderna said in a November 16 news release that it expects to have approximately 20 million doses ready to ship in the U.S. and remains on track to manufacture 500 million to 1 billion doses globally in 2021.

Both companies will seek Emergency Use Authorization (EUA) from the FDA, which would allow the use of the vaccine in recently diagnosed, high-risk patients. Pfizer said in a news release it had submitted for EUA on November 20, while it seems Moderna is planning to achieve its EUA in December.

Once There’s a Vaccine, Is the Pandemic Over?

Not exactly. In fact, even with a vaccine, masks and other “low-tech” interventions, like masks and social distancing, will still be required, Anthony Fauci, MD, said in a recent paper he co-authored for the Journals of the American Medical Association.

“It must be emphasized that these interventions will still be needed after a vaccine is initially available,” the authors wrote. “Even if one or more vaccines have high efficacy and uptake in the population, it will take at least several months for enough people to be vaccinated to confer herd immunity on a population basis.”

The Bottom Line

There seems to be good news ahead, Coffman says.

“We appear to have two highly effective and safe vaccines to fight this virus; both Pfizer’s and Moderna’s vaccines are set to play a role in getting this virus under control,” he says. “Hopefully, by the end of this year, we will have millions of doses of both vaccines we can begin to distribute. Vaccines are critical public health measures to protect the health and safety of communities and slow the spread of this virus.”

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  1. Moderna, Inc. European medicines agency begins rolling review of Moderna's mRNA vaccine candidate against COVID-19 (mRNA-1273) Updated November 17, 2020.

  2. Garde D. Pfizer and BioNTech to submit Covid-19 vaccine data to FDA as full results show 95% efficacy. Stat. Updated November 18, 2020.

  3. Pfizer. Pfizer and Biontech conclude phase 3 study of COVID-19 vaccine candidate, meeting all primary efficacy endpoints. Updated November 18, 2020.

  4. Lerner AM, Folkers GK, Fauci AS. Preventing the spread of SARS-COV-2 with masks and other “low-tech” interventionsJAMA. 2020;324(19):1935.

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