Comirnaty

Pronunciation: Cuh-mir-na-tee
Generic name: COVID-19 Vaccine, mRNA
Other brand names of COVID-19 Vaccine, mRNA include: Comirnaty Fall 2025 Formula
Dosage form: suspension for intramuscular injection (0.3 mL)
Drug class: Viral vaccines

Medically reviewed by Carmen Pope, BPharm. Last updated on Aug 29, 2025.

What is Comirnaty?

Comirnaty (made by Pfizer-BioNTech) is an mRNA COVID-19 vaccine that can be given to adults aged 65 and older or people aged 5 through 64 years with an underlying condition that puts them at high risk for severe COVID-19 outcomes. Comirnaty helps your body develop immunity to SARS-CoV-2, the virus that causes COVID-19.

• Given as a single 0.3 mL dose.
• Updated for fall 2025 to cover LP.8.1.
• If you've had any COVID-19 vaccine before, wait at least 2 months before getting your Comirnaty dose.

Comirnaty does not contain any live virus particles, including those of SARS-CoV-2, the virus that causes COVID-19. It cannot give you COVID-19, although it may not protect everyone who receives the vaccine.

Comirnaty is an mRNA vaccine, which means its mechanism of action is to use messenger RNA (mRNA) to provide instructions for making the spike protein of the COVID-19 virus. Your body then recognizes this spike protein as foreign and produces antibodies and T cells to attack it. This helps your body prepare to fight off the real COVID-19 virus if you're exposed to it.

Comirnaty is an FDA-approved vaccine for use in:

• Adults aged 65 years and older
• People aged 5 through 64 years with at least one underlying condition that puts them at high risk for severe outcomes from COVID-19.

Comirnaty side effects

Side effects that have been reported with Comirnaty or Pfizer-BioNTech COVID-19 vaccines include:

• Severe allergic reactions
• Non-severe allergic reactions such as rash, itching, hives, or swelling of the face
• Myocarditis (inflammation of the heart muscle)
• Pericarditis (inflammation of the lining outside the heart)
• Injection site reactions: pain, swelling, redness, arm pain
• General side effects: tiredness, headache, muscle pain, chills, joint pain, fever, nausea, feeling unwell, swollen lymph nodes (lymphadenopathy), decreased appetite, diarrhea, vomiting, dizziness
• Fainting in association with the injection of the vaccine
• Febrile seizures (convulsions during a fever) in children 5 through 11 years of age

Related/similar drugs

What are the risks of Comirnaty?

Severe Allergic Reactions:

There is a remote chance that Comirnaty could cause a severe allergic reaction. A severe allergic reaction would usually occur within a few minutes to 1 hour after getting a dose. For this reason, the vaccination provider may ask you or your child to stay at the place where you or your child received the vaccine for monitoring after vaccination. Signs of a severe allergic reaction can include:

• Difficulty breathing
• Swelling of the face and throat
• A fast heartbeat
• A bad rash all over the body
• Dizziness and weakness

Myocarditis:

Myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining outside the heart) have occurred in some people who have received mRNA COVID-19 vaccines, including COMIRNATY and Pfizer-BioNTech COVID-19 vaccines.

• Myocarditis and pericarditis following administration of mRNA COVID-19 vaccines have occurred most commonly in males 12 years through 24 years of age.
• In most of these people, symptoms began within a week following vaccination.
• Based on available data, estimated rates of myocarditis and/or pericarditis from 1 through 7 days after getting a dose of the 2023-2024 Formula of mRNA COVID-19 vaccines were approximately 8 cases per million doses in people 6 months through 64 years of age and approximately 27 cases per million doses in males 12 years through 24 years of age.

In most people who have had myocarditis or pericarditis after receiving an mRNA COVID-19 vaccine, symptoms have gone away a few days after receiving treatment with medicines used to reduce inflammation.

• In a study, follow-up information was collected on people who developed myocarditis after receiving the original formula of a COVID-19 vaccine; most people had received an mRNA COVID-19 vaccine.
• Some people in the study reported having heart symptoms approximately 3 months after developing myocarditis.
• Some people in the study had heart MRIs (scans that show detailed images of the heart muscle) initially after developing myocarditis and again approximately 5 months later.
• The initial and follow-up heart MRIs commonly showed signs of injury to the heart muscle, with improvement over time in most people. It is not known if these heart MRI findings might predict long-term heart effects of myocarditis.
• Studies are underway to find out if there are long-term heart effects in people who have had myocarditis after receiving an mRNA COVID-19 vaccine.

You should seek medical attention right away if you or your child has any of the following symptoms after receiving Comirnaty, particularly during the 2 weeks after receiving a dose of the vaccine:

• Chest pain
• Shortness of breath
• Feelings of having a fast-beating, fluttering, or pounding heart

These could be symptoms of myocarditis or pericarditis.

Additional symptoms, particularly in children, may include:

• Fainting
• Unusual and persistent fatigue or lack of energy
• Persistent vomiting
• Persistent pain in the abdomen
• Unusual and persistent cool, pale skin

These may not be all the possible side effects of Comirnaty. Ask your healthcare provider about any side effects that concern you. Report vaccine side effects to the FDA/CDC Vaccine Adverse Event Reporting System (VAERS). The VAERS toll-free number is 1-800-822-7967 or report online to https://vaers.hhs.gov/reportevent.html.

In addition, you can report side effects to Pfizer Inc. at 1-800-438-1985 or www.pfizersafetyreporting.com.

Before receiving Comirnaty

You should not get Comirnaty if you have had a severe allergic reaction to a previous dose of Comirnaty, the Pfizer-BioNTech COVID-19 vaccine, or any of the components in the vaccine (see "Ingredients' below).

Tell your vaccination provider about all of your medical conditions, including if you:

• have any allergies
• have had myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the lining outside the heart)
• have a fever
• have a bleeding disorder or are on a blood thinner
• are immunocompromised or are on a medicine that affects your immune system
• are pregnant or plan to become pregnant
• are breastfeeding
• have received another COVID-19 vaccine
• have ever fainted in association with an injection.

Safety and effectiveness have not been established in children less than 12 years of age. Evidence from clinical studies strongly suggests that a single dose of Comirnaty is ineffective in individuals younger than 6 months of age.

Pregnancy

Comirnaty is generally considered safe for use during pregnancy and major health organizations, including the CDC, ACOG, and AAP, recommend COVID-19 vaccination for pregnant individuals, which includes Comirnaty.

Data from pregnant people who have received mRNA COVID-19 vaccines, including Comirnaty, have not identified any safety concerns for pregnant people or their babies. The vaccine can be administered at any time during pregnancy. Pregnant individuals are at increased risk for severe illness from COVID-19 compared to non-pregnant people and vaccination during pregnancy can help protect both the mother and the baby. Antibodies generated by the vaccine can pass to the fetus, potentially providing some protection to the newborn.

Breastfeeding

It is not known whether Comirnaty is excreted in human milk or its effects on the breastfed infant or milk production/excretion. Consider the benefits versus the risks.

How is Comirnaty given?

Comirnaty is given to you as an injection into a muscle, usually the deltoid muscle of the upper arm.

• 1 injection is usually given (0.3 mL).
• For individuals previously vaccinated with any COVID-19 vaccine, administer the dose of Comirnaty at least 2 months after the last dose of COVID-19 vaccine.

What other drugs will affect Comirnaty?

Tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Tell your healthcare provider if you take:

• a blood thinner, such as warfarin
• a medicine that affects your immune system, such as cyclosporine

Also, tell your healthcare provider if you have received any other COVID-19 vaccines.

Comirnaty ingredients

Active: messenger RNA (mRNA) 

Other ingredients: lipids (((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate), 2 [(polyethylene glycol)-2000]-N,N-ditetradecylacetamide, 1,2-distearoyl-sn-glycero-3-phosphocholine, and cholesterol), tromethamine, tromethamine hydrochloride, and sucrose.

• Comirnaty does not contain preservatives.
• The vial stoppers are not made with natural rubber latex.
• The prefilled syringe tip cap and plunger stopper are not made with natural rubber latex.

Who makes Comirnaty?

Pfizer Inc. manufactures Comirnaty for BioNTech Manufacturing GmbH.

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Further information

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