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Learning about the COVID-19 vaccine's effects on young people with myocarditis.

Low Interventional Cohort Study of Myocarditis/Pericarditis Associated With COMIRNATY in Persons Less Than 21 Years of Age

Phase 4 Interventional Pfizer · NCT05295290

This study is testing how safe the COMIRNATY COVID-19 vaccine is for young people under 21 who have had myocarditis or pericarditis after vaccination, to see how it affects their heart health over time.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment300 (estimated)
Ages0 Years to 20 Years
SexAll
SponsorPfizer Industry-sponsored
Locations32 sites (Birmingham, Alabama and 31 other locations)
Trial IDNCT05295290 on ClinicalTrials.gov

What this trial studies

This clinical trial aims to investigate the safety and long-term effects of the COMIRNATY vaccine in individuals under 21 years old who have experienced myocarditis or pericarditis after vaccination. Participants will be divided into cohorts based on their vaccination status and the timing of their symptoms. The study will compare outcomes between those with vaccine-associated myocarditis and those with myocarditis related to COVID-19 or MIS-C. Cardiac imaging will be utilized to assess the health of the participants over time.

Who should consider this trial

Good fit: Ideal candidates are individuals under 21 years old who have been hospitalized or evaluated in the emergency room for myocarditis or pericarditis after receiving the COMIRNATY vaccine.

Not a fit: Patients who have not received the COMIRNATY vaccine or do not have myocarditis or pericarditis related to vaccination may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide critical insights into the safety of the COVID-19 vaccine in young individuals and help inform vaccination guidelines.

How similar studies have performed: Other studies have explored vaccine safety in various populations, but this specific focus on myocarditis in young individuals post-vaccination is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Cohort 1/2:

  1. Age \<21 years.
  2. Presentation to participating medical center with evaluation in Emergency Room and/or hospitalization.
  3. Received either the 1st, 2nd, 3rd or booster dose(s) of COMIRNATY within 28 days of symptom onset.
  4. Meets criteria of Centers for Disease Control and Prevention case definition of probable or confirmed myocarditis/pericarditis
  5. Capable of giving signed informed consent/assent (by parents/legal guardians of minors and/or patients), which includes compliance with the requirements and restrictions listed in the Informed Consent/Assent Document and in this protocol OR meets criteria for waiver of consent.
* Cohort 3:

  1. Age \<21 years.
  2. Presentation to participating medical center with evaluation in Emergency Room and/or hospitalization.
  3. COVID-19-related disease

     1. Acute COVID-19 infection OR
     2. Multi-system Inflammatory Syndrome in Children Associated with COVID-19 (MIS-C) AND
  4. Probable or confirmed myocarditis/pericarditis\* not temporally related to vaccination with COMINARTY

     1. Probable myocarditis/pericarditis as defined by ≥ 1 new finding of:

        * Elevated troponin above upper limit of normal
        * Abnormal ECG or rhythm monitoring finding consistent with myocarditis
        * Abnormal cardiac function or wall motion abnormalities on echocardiogram
        * cMRI findings consistent with myocarditis OR
     2. Confirmed myocarditis/pericarditis as defined by:

        * Histopathologic confirmation of myocarditis OR
        * Elevated troponin above upper limit of normal AND cMRI findings consistent with myocarditis
  5. Capable of giving signed informed consent/assent (by parents/legal guardians of minors and/or patients), which includes compliance with the requirements and restrictions listed in the Informed Consent/Assent Document and in this protocol OR meets criteria for waiver of consent.

Exclusion Criteria:

1. A plausible alternative etiology for myocarditis/pericarditis, as determined by the site based upon their routine clinical practice for evaluation of potential causes for myocarditis/pericarditis.
2. Pre-existing cardiac conditions that could impact the primary endpoint, including but not limited to, documented history of left ventricular dysfunction (e.g., cardiomyopathy or myocardial infarction), pacemaker, or congenital heart disease, with the exceptions of:

   1. Bicommissural aortic valve with \< trivial stenosis and/or insufficiency
   2. Mitral valve prolapse with \< trivial insufficiency
   3. Hemodynamically insignificant atrial septal or ventricular septal defects.
3. Previous administration with an investigational drug or vaccine within 30 days of enrollment (or as determined by the local requirement).

Where this trial is running

Birmingham, Alabama and 31 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions MyocarditisCOMIRNATYpost-vaccineCOVID-19MIS-C
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.