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Moderna’s vaccine against Covid-19 is strongly effective, the company said Monday, building excitement about the potential of controlling the global pandemic.

The news comes exactly a week after results from Pfizer and BioNTech, which announced broadly similar results. 


The Moderna vaccine reduced the risk of Covid-19 infection by 94.5%. There were 95 cases of infection among patients in the company’s 30,000-patient study. Only five of them occurred in patients who developed Covid-19 after receiving Moderna’s vaccine, mRNA-1273.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, admitted the preliminary data for the Moderna and the Pfizer vaccines — the only two so far to have early estimates of vaccine efficacy — are better than he had anticipated.

“I’d like to say I would have predicted it, but I would not have,” said Fauci, who has often said he would have been satisfied with Covid vaccines that were 70% or 75% efficacy.


“Honestly, I would not have expected that. I thought that was too much to hope for,” he told STAT.

Moderna also released data about the number of patients who had severe Covid-19. There were 11 cases of severe disease, all of them in the placebo group — another point of encouragement for Fauci.

“There was always the concern … since the primary endpoint [of the trial] is just clinically apparent disease, how do we know it’s going to have an impact on severe disease? And the results with severe disease were striking — 11 to zero is very impressive,” he said. At the time of their data release, Pfizer and BioNTech had no severe cases in their study.

Further, Fauci said the Moderna vaccine appears to have been protective in important subsets of participants — the elderly and people from racial and ethnic minority groups, the latter of which make up 37% of the Moderna trial population.

“It wasn’t as if the only people who were protected were the young people. There were people in the elderly, there were people in the minorities,” Fauci said. Efficacy was “really consistent across all groups.”

The companies said they will file for an emergency use authorization with the Food and Drug Administration in the coming weeks, and will file with other global regulators. The European Medicines Agency announced Monday that it has begun a rolling review of the Moderna vaccine.

Moderna said in its press release that there were no significant safety concerns. Severe events that occurred in greater than 2% of patients included fatigue and muscle pain, which happened in nearly 1 patient in 10, and headache and achiness. These events were “generally short-lived,” the company said.

The vaccine was designed with assistance from NIAID’s vaccine research center; development of the vaccine has been supported by nearly $1 billion in grants from the Biomedical Advanced Research and Development Authority. 

Moderna has a $1.525 billion contract to provide the United States with 100 million doses of the vaccine through Operation Warp Speed, the government’s fast-track program for Covid-19 vaccines, therapeutics, and diagnostics. The contract gives the U.S. government an option to purchase an additional 400 million doses.

The Moderna results come one week after the Pfizer-BioNTech collaboration reported that a preliminary analysis of their mRNA vaccine suggested it was strongly protective. The Pfizer analysis, which was conducted after 94 people in the 43,000-person trial had contracted symptomatic Covid disease, showed there were 90% fewer cases among the people who received two doses of vaccine than among those who received two placebo injections. 

These figures are both a relief and a surprise. Expectations for these vaccines had not run quite so high, with many experts cautioning that the shots might offer modest protection along the lines of what is seen with influenza vaccines. The FDA had previously told manufacturers that it would consider for licensure vaccines with an efficacy that exceeded 50%. 

Both Moderna’s trial and Pfizer’s are continuing and efficacy figures could decline by the time the trials are complete. It is often the case that a vaccine performs less well in the real world than it does in the setting of a clinical trial, experts warn. 

Furthermore, data from the two trials do not indicate how long the protection afforded by the vaccines lasts. That can only be determined over time as large numbers of people are vaccinated. 

The Moderna results, like those from Pfizer, were disclosed in a press release, not a scientific article, and limited details are public. 

The Moderna and Pfizer mRNA vaccines, if approved, will become the first licensed products using an approach that has been thought to hold enormous promise as a tool for responding to new disease threats.  The vaccines contains genetic material that prompt the body to create a protein that sits on the exterior of the virus, effectively training the immune system to recognize it as an invader.  

The Moderna vaccine is given in two doses, 28 days apart.

The 30,000-person trial included 11,000 volunteers from communities of color, making up 37% of the total study population. It also included more than 7,000 volunteers over the age of 65 and more than 5,000 people under 65 who have high-risk medical conditions that put them at high risk of suffering from a severe infection, should they contract Covid, things like diabetes, severe obesity and heart disease. 

Moderna shares were up 10% to $98 in early Monday trading. 

Correction: This story has been updated to make clear that there were 95 infections among all patients in the study, with just five of them occurring in patients who received the vaccine. This story has also been updated with comments from Anthony Fauci.

  • I’ve read in the news that Moderna and Pfizer vaccines are safe and 94.5 to 95% effective. I have prayed a lot since June that you can come up with these vaccines. Now that you have the vaccines; what are you waiting for. There are plenty of people sick and dying of the corona virus. Can you please distribute, administer, inject, the vaccines to the people NOW? Today is November 18, 2020. Please start to distribute, administer, and inject the vaccines to the people who wants it, so that those who are sick or got sick with the virus will be healed and cured. TIME IS RUNNING OUT. SO PLEASE!!!

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