A Study to Investigate Cardiac Troponin Levels After mRNA-1273.712 Vaccine in Participants 12 Through 30 Years of Age

The primary objective of this study is to assess cardiac troponin I (cTnI) values in participants who received mRNA-1273.712 or placebo.


Eligibility Criteria:
Inclusion Criteria:

1. Investigator's assessment that participant understands and is willing and physically able to comply with protocol-mandated follow-up, including all procedures.
2. Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF).
3. Contraceptive use by participants should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.

Exclusion Criteria:

1. History of anaphylaxis or severe hypersensitivity reaction requiring medical intervention after receipt of any mRNA vaccine or therapeutic or any components of an mRNA vaccine or therapeutic.
2. Has known history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection within 3 months prior to enrollment.
3. Has a documented history of myocarditis or pericarditis.
4. Is acutely ill or febrile (temperature ≥38.0 degrees Celsius \[°C\]/100.4 degrees Fahrenheit \[°F\]) less than 72 hours prior to or at the Screening Visit or Day 1.
5. Has known conditions that may cause elevated cTnI.

   * Cardiac disease/conditions including rhythm disorders and congenital heart disease
   * Diabetes
   * Uncontrolled hypertension (defined as systolic blood pressure \>140 millimeter of mercury (mmHg) or diastolic blood pressure \>90 mmHg)
   * Alcohol or substance abuse
   * Kidney disease
   * Severe obesity, defined as body mass index (BMI) ≥40 kilograms per square meter (kg/m\^2) (\>20 years) or severe obesity defined as BMI for sex and age ≥120% of the 95th percentile \[BMI ≥35 kg/m\^2\] (for 12 to 20 years)
6. Currently has symptomatic acute or unstable chronic disease requiring medical or surgical care, to include significant change in therapy or hospitalization for worsening disease, at the discretion of the Investigator.
7. Has a medical, psychiatric, or occupational condition that may pose additional risk as a result of participation, or that could interfere with safety assessments or interpretation of results according to the Investigator's judgment.
8. Reported history of congenital or acquired immunodeficiency (eg, human immunodeficiency virus \[HIV\]), immunosuppressive condition or immune-mediated disease, asplenia, or recurrent severe infections disease.
9. History of Guillain-Barré syndrome.
10. Receipt of the following:

    * Coronavirus disease 2019 (COVID-19) vaccine within 3 months prior to the first injection or if planning to receive at any time during the study (except for study intervention).
    * Any other licensed vaccine within 28 days before the study injection or planned receipt prior to end of study (EOS).
    * Systemic immunosuppressants or immune-modifying drugs for \>14 days in total within 6 months prior to Screening (for corticosteroids ≥10 milligrams (mg)/day of prednisone equivalent) or is anticipating the need for immunosuppressive treatment at any time during participation in the study.
    * Systemic immunoglobulins or blood products within 3 months prior to the Screening/Baseline Visit or plans for receipt during the study.