Moderna's mRNA-1273 vaccine is based on the SARS-CoV-2 spike glycoprotein antigen encoded by RNA and formulated in lipid nanoparticles. The predominant T-cell response elicited by the vaccine was CD4+ T cells, mostly of the Th-1 phenotype. The vaccine triggers the immune system to learn to react defensively, producing an immune response against SARS-CoV-2, according to the FDA.

In a December 17 meeting of the FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC), committee members voted 20 to 0 with one abstention to recommend an EUA for the candidate. Briefing documents provided by the company prior to the meeting supported vaccine efficacy of 94.1% and a satisfactory safety profile.

In the hearing, representatives from the FDA and Moderna addressed cases of anaphylactic reactions to mRNA-1273, with investigations into these cases conducted rapidly. The EUA covers use of the vaccine in individuals 18 years of age and older.

The mRNA-1273 vaccine is administered as a series of two doses, one month apart. Moderna supported its EUA submission with data from 30,351 participants enrolled in an ongoing, randomized, placebo-controlled study conducted in the U.S. In all, 15,185 participants received the vaccine and 15,166 received a saline placebo.

Moderna followed participants for a median of more than two months after they received the second dose. Side effects reported most often included pain at the injection site, tiredness, headache, muscle pain, chills, joint pain, swollen lymph nodes in the same arm as the injection, nausea and vomiting, and fever.

The FDA noted that more people experienced these side effects after the second dose than the first dose. The agency advised healthcare providers and vaccine recipients to expect that there may be some side effects after either dose, but even more so after the second dose.

FDA Commissioner Dr. Stephen Hahn pointed to the speed with which the agency was able to review both vaccines under the EUA process.

"With the availability of two vaccines now for the prevention of COVID-19, the FDA has taken another crucial step in the fight against this global pandemic that is causing vast numbers of hospitalizations and deaths in the United States each day," Hahn said in a statement.

FDA committee votes favorably for Moderna COVID-19 vaccine EUA
Moderna's messenger RNA (mRNA) COVID-19 vaccine candidate, mRNA-1273, received a favorable recommendation on December 17 from an advisory committee to...

Moderna's vaccine data support high efficacy, safety prior to FDA meeting
Moderna has published information supporting a 94.1% efficacy rate for its messenger RNA (mRNA) COVID-19 vaccine, mRNA-1273. The company made the data...

FDA issues EUA for Pfizer, BioNTech COVID-19 vaccine
The U.S. Food and Drug Administration (FDA) has issued an emergency use authorization (EUA) for the Pfizer-BioNTech COVID-19 vaccine. The move comes after...

FDA in final stages before issuing Pfizer, BioNTech EUA
The U.S. Food and Drug Administration (FDA) has informed Pfizer and BioNTech that it will work rapidly toward the finalization and issuance of an emergency...

Pfizer, BioNTech's COVID-19 vaccine shows 95% efficacy
In a trial of more than 40,000 participants, Pfizer-BioNTech's COVID-19 vaccine showed a 95% efficacy against the SARS-CoV-2 virus, according to results...