Comirnaty
Comirnaty (Pfizer-BioNTech COVID-19 vaccine) is an mRNA vaccine that's used to prevent infection from the virus that causes COVID-19 (coronavirus disease 2019). It's FDA-approved for people 12 years and older and has an emergency use authorization (EUA) for children 6 months to 11 years of age. This vaccine is given as an injection into the muscle by a healthcare provider. You can get an updated Comirnaty booster shot once you're fully vaccinated against the virus. Common side effects include pain at the injection site, tiredness, headache, and chills.
What is Comirnaty?
What is Comirnaty used for?
Prevention of COVID-19 infections in people ages 12 and older
Prevention of COVID-19 infections in children ages 6 months to 11 years - EUA only
How Comirnaty works
Comirnaty is an mRNA vaccine. This vaccine contains lab-made mRNA (genetic information) that teaches your body to make a part of the "spike protein" found on the virus that causes COVID-19.
Your immune system recognizes that this harmless spike protein doesn't belong in your body. This triggers your immune system to make antibodies against the protein. The antibodies tell other immune cells to get rid of it.
Your immune system learns and remembers what the spike protein of the COVID-19 virus looks like. So when you get infected with the COVID-19 virus, your immune system is ready to fight and protect you from infection.
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What are the side effects of Comirnaty?
Common Side Effects
- Pain at the injection site
- Feeling tired
- Headache
- Chills
- Muscle pain
- Joint pain
- Fever
Other Side Effects
- Swelling and redness at the injection site
- Diarrhea
- Nausea
- Vomiting
- Feeling unwell
- Poor appetite
- Excessive sweating
- Weakness
- Night sweats
Serious Side Effects
- Heart inflammation (swelling): chest pain, shortness of breath, a racing heart
- Serious allergic reactions: trouble breathing, throat tightness, fainting, hives, rash, swelling of your face, lips, tongue, or throat
Source: DailyMed
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The following side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
- Heart muscle inflammation—unusual weakness or fatigue, shortness of breath, chest pain, fast or irregular heartbeat, dizziness, swelling of the ankles, feet, or hands
Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):
Pros and cons of Comirnaty
Pros
Recommended by the CDC to prevent COVID-19 infection
Authorized for children as young as 5 years old
Need only 1 shot to be fully vaccinated for people 5 years and older
Cons
Doesn't guarantee that you won't get COVID-19 (but helps lessen severity)
Commonly causes temporary pain at injection site, fever, and tiredness
Pharmacist tips for Comirnaty
Comirnaty is injected into your muscle by a healthcare provider at an office, clinic, or pharmacy.
Comirnaty can cause mild side effects like pain at the injection site, tiredness, muscle aches, fever, and chills. These are normal signs that your immune system is working to build protection against the virus. They should go away on their own within a few days.
You can use a clean, cool, wet washcloth over the area where you got your injection to help relieve any pain you might feel. Moving your arm around can also help lower arm soreness.
Before receiving Comirnaty, don't take any pain-relieving medications, like ibuprofen (Advil, Motrin) or acetaminophen (Tylenol), or antihistamines, like diphenhydramine (Benadryl), just to try to prevent side effects. We don't know how these medications might affect how well the vaccine works. If needed, ask your provider what some possible treatment options are for you after getting Comirnaty.
Let your provider know if any side effects get worse after 24 hours of getting the vaccine or if they don't go away after a few days.
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Frequently asked questions about Comirnaty
The updated Comirnaty (Pfizer COVID-19 vaccine) was approved by the FDA because the immune responses in people who got the updated single dose were similar to those who received the previously approved 2-dose series. Talk to your provider if you have more questions about how well the vaccine works.
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What are the risks and warnings for Comirnaty?
Comirnaty can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Heart inflammation (swelling)
Risk factors: Males between age 12 and 17 | Second dose of Comirnaty
Although rare, Comirnaty can raise the risk of heart inflammation, such as myocarditis (swelling of the heart muscle) and pericarditis (swelling of the tissue lining the outside of the heart).
This can happen particularly within the first week after a second dose of Comirnaty. Males between 12 and 17 years old are at the highest risk. Most people who develop this type of heart inflammation from the vaccine recover after getting appropriate care in the hospital.
Let your provider know right away if you experience chest pain, shortness of breath, or a racing heart, as these can be signs of heart inflammation.
Fainting
Some people have fainted shortly after getting vaccines. Tell your provider if you have a history of fainting after vaccinations. They can keep a close eye on you for about 15 minutes after you get Comirnaty. To prevent injuries from fainting, it's best to sit down while you're getting your vaccine and while your provider is monitoring you.
Lowered response in people with weakened immune systems
Risk factors: Conditions that lower the immune system | Taking medications that lower the immune system
People with weakened immune systems might have a lowered response to Comirnaty. This includes people with certain conditions and those taking medications that can lower the immune system (e.g., organ transplant, cancer medications, long-term corticosteroid use).
Continue to take the necessary precautions to prevent COVID-19 infection if you have a weak immune system. Let your provider know about your medical history and medication list. Your provider can discuss more ways to help protect yourself from infection.
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Comirnaty dosage forms
Typical dosing for Comirnaty
Comirnaty is injected into the muscle by a healthcare provider. Each injection has 0.3 mL of medication.
Discuss with your healthcare provider about whether Comirnaty is appropriate for you and when to get your dose(s).
Primary series (for people who haven't been previously vaccinated with any COVID-19 vaccine)
Adults and children 5 years and older: The typical dose is 1 injection into the muscle.
Children 6 months to 4 years: In general, the typical dose is 1 injection into the muscle. This is followed by a second dose 3 weeks later. And finally, a third dose given 8 weeks after the second dose.
Certain children with a weakened immune system: Speak with your healthcare provider about your child's dosing schedule for Comirnaty. Sometimes, your child might need additional doses.
Booster dose (for people who've been previously vaccinated with any COVID-19 vaccine): The typical dose is 1 injection into the muscle at least 2 months after your most recent COVID-19 vaccine dose.
Note: The CDC recommendations about the timing of Comirnaty vaccine doses might be different. Ask your healthcare provider if you have any questions about how many Spikevax shots you need and when to get them.
How much does Comirnaty cost?
What are alternatives to Comirnaty?
Prevention of COVID-19 infections in people ages 12 and older
Prevention of COVID-19 infections in children ages 6 months to 11 years - EUA only
Prevention of COVID-19 infection in people aged 12 years and older
Prevention of COVID-19 infections in people 12 years and older
Prevention of COVID-19 infections in children 6 months to 11 years - EUA only
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References
Best studies we foundAmerican College of Obstetricians and Gynecologists. (2023). COVID-19 Vaccination considerations for obstetric–gynecologic care
Centers for Disease Control and Prevention. (n.d.). COVID-19 vaccine effectiveness update.
Centers for Disease Control and Prevention. (n.d.). How mRNA COVID-19 vaccines work.
Centers for Disease Control and Prevention. (2023). FDA takes action on updated mRNA COVID-19 vaccines to better protect against currently circulating variants.
Centers for Disease Control and Prevention. (2024). COVID-19 vaccines while pregnant or breastfeeding.
Centers for Disease Control and Prevention. (2024). Interim clinical considerations for use of COVID-19 vaccines in the United States.
Centers for Disease Control and Prevention. (2024). Stay up to date with COVID-19 vaccines.
Pfizer Laboratories Div Pfizer Inc. (2024). Comirnaty- covid-19 vaccine, mrna injection, suspension [package insert]. DailyMed.
U.S. Food and Drug Administration. (2023). Pfizer-BioNTech COVID-19 vaccine.
Wolicki, J., et al. (2021). Vaccine administration. Centers for Disease Control and Prevention.
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