General Information

Comirnaty (COVID-19 Vaccine, mRNA) contains messenger RNA (mRNA), which is genetic material. The vaccine contains a small piece of the SARS-CoV-2 virus’s mRNA that instructs cells in the body to make the virus’s distinctive “spike” protein. When a person receives this vaccine, their body produces copies of the spike protein, which does not cause disease, but triggers the immune system to learn to react defensively, producing an immune response against SARS-CoV-2. 

Comirnaty is specifically indicated for prevention of COVID-19 in individuals 16 years of age and older

• It is also authorized under Emergency Use Authorization (EUA) to be administered for emergency use to:
  • prevent COVID-19 in individuals 12 through 15 years, and
  • provide a third dose to individuals 12 years of age and older who have been determined to have certain kinds of immunocompromise

Comirnaty is supplied as a suspension for intramuscular injection administered as a series of two doses (0.3 mL each) 3 weeks apart.

Mechanism of Action

Comirnaty (COVID-19 Vaccine, mRNA) contains messenger RNA (mRNA), which is genetic material. The vaccine contains a small piece of the SARS-CoV-2 virus’s mRNA that instructs cells in the body to make the virus’s distinctive “spike” protein. When a person receives this vaccine, their body produces copies of the spike protein, which does not cause disease, but triggers the immune system to learn to react defensively, producing an immune response against SARS-CoV-2. The nucleoside-modified mRNA in Comirnaty is formulated in lipid particles, which enable delivery of the mRNA into host cells to allow expression of the SARS-CoV-2 S antigen. The vaccine elicits an immune response to the S antigen, which protects against COVID-19.

Side Effects

Adverse effects associated with the use of the Pfizer-BioNTech COVID-19 vaccine may include, but are not limited to, the following:

• pain at the injection site
• fatigue
• headache
• muscle pain
• chills
• joint pain
• fever

Severe allergic reactions have been reported following the Pfizer-BioNTech COVID-19 Vaccine during mass vaccination outside of clinical trials. Do not administer Pfizer-BioNTech COVID-19 Vaccine to individuals with known history of a severe allergic reaction (e.g., anaphylaxis) to any component of the Pfizer-BioNTech COVID-19 Vaccine. Appropriate medical treatment used to manage immediate allergic reactions must be immediately available in the event an acute anaphylactic reaction occurs following administration of Pfizer-BioNTech COVID-19 Vaccine.

Clinical Trial Results

Comirnaty was granted Emergency Use Authorization based on available data providing clear evidence that it may be effective in preventing COVID-19. The data also support that the known and potential benefits outweigh the known and potential risks. The FDA expects Pfizer and BioNTech to continue their clinical trials to obtain additional safety and effectiveness information and pursue approval (licensure).

The effectiveness data to support the EUA was based on an analysis of 36,523 subjects in the ongoing randomized, placebo-controlled international study, the majority of whom reside in the U.S., who did not have evidence of SARS-CoV-2 infection through seven days after the second dose. Among these subjects, 18,198 received the vaccine and 18,325 received placebo. The vaccine was 95% effective in preventing COVID-19 disease, with eight COVID-19 cases in the vaccine group and 162 in the placebo group. Of these 170 COVID-19 cases, one in the vaccine group and three in the placebo group were classified as severe. At this time, data are not available to make a determination about how long the vaccine will provide protection, nor is there evidence that the vaccine prevents transmission of SARS-CoV-2 from person to person.  The FDA granted full approval based on long term follow-up data from the Phase 3 trial, where the vaccine’s high efficacy and favorable safety profile were observed up to six months after the second dose. Analysis of 927 confirmed symptomatic cases of COVID-19 demonstrates the vaccine is highly effective with 91.3% vaccine efficacy observed against COVID-19, measured seven days through up to six months after the second dose. The vaccine was 100% effective in preventing severe disease as defined by the U.S. Centers for Disease Control and Prevention and 95.3% effective in preventing severe disease as defined by the U.S. Food and Drug Administration.