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Get a better understanding of Moderna COVID-19 Vaccine (2023-2024 Formula) with our helpful fact sheet.

Important Safety Information

What should you mention to the vaccination provider before your child gets Moderna COVID-19 Vaccine (2023-2024 Formula)? Tell the vaccination provider about all your child’s medical conditions, including if your child:

  • has any allergies

  • has had myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the lining outside the heart)

  • has a fever

  • has a bleeding disorder or is on a blood thinner

  • is immunocompromised or is on a medicine that affects your or your child’s immune system

  • is pregnant

  • is breastfeeding

  • has received another COVID-19 vaccine

  • has ever fainted in association with an injection

Who should not get Moderna COVID-19 Vaccine (2023-2024 Formula)? Your child should not get Moderna COVID-19 Vaccine if your child had:

  • a severe allergic reaction after a previous dose of any Moderna COVID-19 Vaccine formulation

  • a severe allergic reaction to any ingredient in these vaccines

What are the risks of Moderna COVID-19 Vaccine (2023-2024 Formula)? Severe allergic reactions: there is a remote chance that the vaccine could cause a severe allergic reaction. A severe allergic reaction would usually happen within a few minutes to one hour after getting a dose. 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 (inflammation of the heart muscle) and pericarditis (inflammation of the lining outside the heart) have happened in some people who have received mRNA COVID-19 vaccines, most commonly in young adult males 18 years through 24 years of age. In most of these individuals, symptoms began within a few days following vaccination. The chance of having this occur is very low. Seek medical attention right away if your child has any of the following symptoms after receiving the vaccine, particularly during the 2 weeks after your child receives a dose:

  • Chest pain

  • Shortness of breath or difficulty breathing

  • Feelings of having a fast-beating, fluttering, or pounding heart

Additional symptoms, particularly in children, may include:

  • Fainting

  • Unusual and persistent irritability

  • Unusual and persistent poor feeding

  • Unusual and persistent fatigue or lack of energy

  • Persistent vomiting

  • Persistent pain in the abdomen

  • Unusual and persistent cool, pale skin

Side effects that have been reported in clinical trials with Moderna COVID-19 vaccines include:

  • Injection site reactions: pain, tenderness and swelling of the lymph nodes in the same arm of the injection or in the groin, swelling (hardness), and redness

  • General side effects: fatigue, headache, muscle pain, joint pain, chills, nausea and vomiting, fever, rash, irritability/crying, sleepiness, and loss of appetite

Side effects that have been reported during post-authorization use include:

  • Severe allergic reactions

  • Urticaria (itchy rash/hives)

  • Myocarditis (inflammation of the heart muscle)

  • Pericarditis (inflammation of the lining outside the heart)

  • Fainting in association with injection of the vaccine

These may not be all the possible side effects. Serious and unexpected side effects may occur. The possible side effects are still being studied.

What should I do about side effects? If your child experiences a severe allergic reaction, call 9-1-1, or go to the nearest hospital. Call the vaccination provider or your child’s healthcare provider if your child has any side effects that bother your child or do not go away. Report vaccine side effects to FDA/CDC Vaccine Adverse Event Reporting System (VAERS). The VAERS toll-free number is 1-800-822-7967 or report online to  Please include “Moderna COVID-19 (2023-2024 Formula) EUA” in the first line of box #18 of the report form.   In addition, you can report side effects to ModernaTX, Inc. at 1-866-MODERNA (1-866-663-3762). Please see the Moderna COVID-19 Vaccine (2023-2024 Formula) Fact Sheet for Recipients and Caregivers for more information.