Peer-reviewed report on Modern COVID-19 vaccine published

News Release

Wednesday 30 December 2020

Data from Phase 3 clinical trials confirm that the vaccine is effective.


The research vaccine, known as mRNA-1273, was 94.1% effective in preventing symptomatic coronavirus disease 2019 (COVID-19), according to preliminary results of a phase 3 clinical trial conducted in the New England Journal of Medicine. The vaccine has also been shown to be effective in preventing severe COVID-19. Investigators have identified no safety concerns and no evidence of an increased respiratory illness associated with the vaccine (VAERD).

The vaccine was co-developed by Moderna, Inc., a biotechnology company in Cambridge, Massachusetts, and the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. Moderna and NIAID previously shared the first results of the COVE trial. On December 18, 2020, the FDA issued an emergency authorization enabling Moderna to make the vaccine available for the prevention of COVID-19 in adults in the United States.

The trial was led by lead investigators Lindsey R. Baden, managing director of Brigham and Women’s Hospital in Boston, Hana M. El-Sahly, managing director of Baylor College of Medicine in Houston, and Brandon Essink, managing director, of Meridian Clinical Research. The trial was implemented under the US Government’s Operation Warp Speed ​​program and supported by NIAID and the Biomedical Advanced Research and Development Authority (BARDA) of the US Department of Health and Human Services’ Office of the Assistant Secretary for Readiness and Response .

The trial began on July 27, 2020, enrolling 30,420 adult volunteers at clinical research sites across the United States. Volunteers were randomly assigned 1: 1 to receive two doses of 100 micrograms (mcg) of the study vaccine or two shots of saline with 28 days apart. The average age of volunteers is 51 years. About 47% are female, 25% are 65 years or older and 17% are younger than 65 with medical conditions that pose a higher risk for severe COVID-19. About 79% of participants are white, 10% are black or African American, 5% are Asian, 0.8% are Native American or Alaskan natives, 0.2% are Native Hawaiian residents or other Pacific Islanders , 2% are multiracial and 21% (of any race) are Spanish or Latino.

From the start of the trial until November 25, 2020, investigators recorded 196 cases of symptomatic COVID-19 that occurred among the participants, at least 14 days after they received their second shot. One hundred and eighty-five cases (of which 30 were classified as severe COVID-19) occurred in the placebo group and 11 cases (of which 0 were classified as severe COVID-19) occurred in the group that received mRNA-1273. The incidence of symptomatic COVID-19 was 94.1% lower in participants receiving mRNA-1273 compared with those receiving placebo.

Investigators observed 236 cases of symptomatic COVID-19 among participants at least 14 days after receiving their first shot, with 225 cases in the placebo group and 11 cases in the group receiving mRNA-1273. The vaccine efficacy was 95.2% for this secondary analysis.

According to the authors, there were no safety issues regarding vaccination. Local reactions to the vaccine were generally mild. Approximately 50% of participants who received mRNA-1273 experienced moderate to severe side effects after the second dose – such as fatigue, muscle aches, joint pain, and headaches – which disappeared in most volunteers within two days.

Investigators also found no evidence of VAERD among those who received mRNA-1273. This rare complication was seen in individuals vaccinated with a completely inactivated respiratory synthesis virus (RSV) vaccination in the 1960s, before there was an ability to define protein structures and measure immune responses with precision. VAERD can occur if a vaccine elicits an immune response that is not strong enough to protect against infection.

Although mRNA-1273 is very effective in preventing symptomatic COVID-19, there are not enough data available to conclude whether the vaccine can affect SARS-CoV-2 transmission. Preliminary test data suggest that some prevention of asymptomatic infection after a single dose may occur. Additional analyzes are underway on the prevalence of asymptomatic infection and viral poisoning after infection to understand the impact of the vaccine on infectivity.

The authors concluded by discussing the unprecedented efficacy of candidate vaccine development, noting: “this process demonstrates what is possible in the context of motivated collaboration between key sectors of society, including academia, government, the industry, regulators and the wider community. “


LR Baden, et al. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. The New England Journal of Medicine. DOI: 10.1056 / NEJMoa2035389.


The director of NIAID, Anthony S. Fauci, is available to comment on this study. John R. Mascola, MD, director of the NIAID’s vaccine research center, is also available for comment.


To schedule interviews, contact the NIAID News and Science Writing Branch, (301) 402-1663, [email protected].

NIAID conducts and supports research – at NIH, across the United States and worldwide – to study the causes of infectious and immune-mediated diseases, and to develop better ways to prevent, diagnose, and treat these diseases. News reports, fact sheets and other NIAID related material are available on the NIAID website.

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