Moderna's COVID-19 vaccine nearly 95% effective

US company Moderna have just released their early phase 3 clinical trial results for their COVID-19 vaccine which is nearly 95% effective. These results come just a week after Pfizer’s vaccine results.

US biotechnology company Moderna has been working on a vaccine to potentially treat COVID-19 since mid-January, and have just released their phase 3 results for their mRNA-1273 vaccine. The DSMB (Data Safety Monitoring Board) has informed Moderna that they have met the criteria pre-specified in the study for efficacy with their vaccine efficacy at 94.5%.

The overall effectiveness has been remarkable… it’s a great day”

Tal Zaks, Chief Medical Officer, Moderna

About Moderna's Study

Their study, known as the COVE study, has enrolled more than 30,000 participants in the US and has been conducted in collaboration with NIH (National Institutes of Health), BARDA (Biomedical Advanced Research and Development Authority), and NIAID (National Institute of Allergy and Infectious Diseases).

Half of the 30,000 participants were given two doses of the vaccine whilst the other half received a placebo.

The first interim analysis was performed on 95 cases, of which in the placebo group there were 90 cases of COVID-19 compared to 5 cases observed in the mRNA-1273 group. This resulted in a vaccine efficacy of 94.5% (p < 0.0001).

The secondary endpoint saw 11 severe cases of COVID-19 in the first interim analysis, however, all 11 cases were in the placebo group.

The interim analysis also reported no significant safety concerns and reported that the vaccine was well tolerated with the majority of adverse reactions being mild to moderate in their severity. The data is still subject to change due to the ongoing analysis of further data and their final results.


Image Credit: BaLL LunLa/

Further information

The vaccine designed by Moderna can also be stored at minus 20 degrees Celsius for up to six months and can be kept in a standard fridge for up to a month making it easier to store compared to Pfizer’s vaccine that can only be stored in ultra-cold storage at minus 75 degrees Celsius.

However, the data for the trial is still in its preliminary data and many questions still remain unanswered. We currently do not know how long immunity will last as volunteers will need to be monitored for a longer period before we can judge.

There is also currently no data on how well the vaccine performs in older age groups who are most vulnerable to dying from COVID-19.

As more cases develop leading up to their final analysis, Moderna expects that the point estimate for the efficacy of the vaccine may change and they currently plan to submit data from the full Phase 3 COVE study for peer-review publication.

This is a pivotal moment in the development of our COVID-19 vaccine candidate”

The recent breakthrough research in vaccine trials gives great hope that vaccines will be soon able to end the pandemic.

Emily Henderson

Written by

Emily Henderson

Emily Henderson graduated with a 2:1 in Forensic Science from Keele University and then completed a PGCE in Chemistry. Emily particularly enjoyed discovering new ideas and theories surrounding the human body and decomposition. In her spare time, Emily enjoys watching crime documentaries and reading books. She also loves the outdoors, enjoying long walks and discovering new places. Emily aims to travel and see more of the world, gaining new experiences and trying new cultures. She has always wanted to visit Australia and Indonesia.


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