Moderna’s COVID-19 Vaccine Shows 94.5% Efficacy

Moderna's COVID-19 Vaccine has an efficacy of 94.5%
Credit: Dado Ruvić/Reuters
  • Earlier this year, Moderna began working on a COVID-19 vaccine in collaboration with the National Institutes of Health.
  • In late July, the US-based biotech company announced the commencement of its Phase III clinical trials.
  • According to the results, released Monday, the vaccine has proven efficacy of 94.5% in the phase III trials.

Moderna is the second US-based company to have announced promising results from its phase 3 clinical trials. According to the interim analysis results released Monday, Moderna’s vaccine is 94.5% effective at preventing COVID-19. 

It was one of the greatest moments in my life and my career. It is absolutely amazing to be able to develop this vaccine and see the ability to prevent symptomatic disease with such high efficacy

Dr. Tal Zacks, Moderna’s chief medical officer

Moderna’s Vaccine is Based on mRNA Technology

Similar to Pfizer and BioNTech, Moderna’s vaccine is also based on messenger RNA (mRNA) technology. This past week, Pfizer and BioNTech announced their interim analysis result which showed an efficacy of 90%.

The mRNA is delivered via the vaccine into the body. This tricks the body into producing spike protein of the SARS-CoV-2 virus. The body then starts producing antibodies against these. These antibodies then help fight off any future COVID-19 infections.

Mechanism of Moderna’s mRNA-based vaccine.
Source: Moderna, Inc

There has always been skepticism about mRNA — it’s brand new and would it work? What we saw in the trials is there was no real safety concern, and the efficacy is quite impressive. We saw nearly identical results [with Pfizer and Moderna] and it almost really validates the mRNA platform.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases

In July, Moderna began enrollment for the phase III trial of its Coronavirus Efficacy (COVE) study. The researchers recruited 30,000 participants from all over the U.S, half of which received a placebo while the other half received the vaccine. The vaccine is given in two doses several weeks apart.

Interim Analysis Reveals 94.5% Efficacy

The interim analysis is based on 95 confirmed COVID-19 cases observed two weeks following the second dose of the vaccine. 

Among the placebo group, 90 participants developed COVID-19 of which 11 had a severe infection. Whereas only 5 participants in the vaccine group developed the disease. None of which had a severe infection. Thus, resulting in a 94.5% vaccine efficacy. Furthermore, the interim analysis reported the absence of any significant safety concerns. 

Pfizer vs Moderna

Although both vaccines have similar efficacies, Moderna’s vaccine has a bit of an advantage over Pfizer’s. 

According to Moderna, their vaccine can be stored at temperatures of minus 20 degrees Celsius for up to six months. Whereas Pfizer’s vaccine requires temperatures of -70 to -80 degrees Celsius, making delivery of the vaccine more difficult. 

However, Moderna’s vaccine comes with a higher price tag. Especially taking into consideration the two-dose course of the vaccine.

Currently, Moderna is planning on submitting the vaccine to the FDA for an Emergency Use Authorization. This will be based on the company’s final analysis report. The report is meant to include 151 confirmed COVID-19 cases observed on a two-month follow-up.


Moderna’s COVID-19 Vaccine Candidate Meets its Primary Efficacy Endpoint in the First Interim Analysis of the Phase 3 COVE Study. (2020, November 16). Retrieved November 16, 2020, from


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