A Safety and Immune Response Study to Evaluate Varying Doses of an mRNA Vaccine Against Coronavirus Disease 2019 (COVID-19) in Healthy Adults

1. Has a new onset, clinically significant, abnormal biochemistry or hematology finding \[defined as greater than or equal to (\>=) Grade 1\] at screening (participants with Grade 1 laboratory abnormalities that have been stable for at least 6 months before enrollment may be included in the study).

2. Has any medical disease or condition that, in the opinion of the investigator, precludes study participation. This includes any acute, subacute, intermittent, or chronic medical disease or condition that would place the participant at an unacceptable risk of injury, render the participant unable to meet the requirements of the protocol, or may interfere with the evaluation of responses or the participant's successful completion of the trial.

3. Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination (no laboratory testing required).

4. History of myocarditis, pericarditis, second- and third-degree heart block or idiopathic cardiomyopathy, or presence of any medical condition that increases risk of myocarditis or pericarditis, including cocaine abuse, cardiomyopathy, endomyocardial fibrosis, hypereosinophilic syndrome, hypersensitivity myocarditis eosinophilic granulomatosis with polyangiitis, persistent myocardial viral infection (e.g., due to enterovirus or adenovirus).

5. Has an acute febrile illness with a temperature \>=38.0 degree Celsius (°C) or \>=100.4 degree Fahrenheit (°F) observed by the participant or at the study site within 72 hours prior to study vaccination. Participants with suspected COVID-19 symptoms should be excluded and referred for medical care.

6. Has a history of hypersensitivity or severe allergic reaction, including anaphylaxis, generalized urticaria, angioedema, and other significant reactions to any previous vaccine, or any component of the study vaccine.

7. Has a body mass index greater than (\>) 40 Kilograms meter per square (kg/m\^2).

8. Has had known close contact with anyone who had a confirmed SARS-CoV-2 infection within 14 days before study vaccination.

9. Has a history of documented SARS-CoV-2 infection or COVID-19 within 6 months before the date of screening visit.

10. Has any self-reported or medically documented clinically significant medical or psychiatric condition. Significant medical conditions include, but are not limited to, the following:

1. Moderate or severe respiratory disease (e.g., chronic obstructive pulmonary disease, asthma).

2. Uncontrolled hypertension, defined as an average systolic blood pressure \>= 140 millimeters of mercury (mmHg) or an average diastolic blood pressure \>= 90 mmHg, based on an average of up to 3 blood pressure measurements.

3. Clinically significant cardiovascular disease (e.g., congestive heart failure, cardiomyopathy, ischemic heart disease).

4. Neurological or neurodevelopmental conditions (e.g., Down syndrome, dementia, chronic migraine not controlled by medication, epilepsy, stroke or seizures in the last 3 years, encephalopathy, focal neurologic deficits, Guillain- Barré syndrome, encephalomyelitis, or transverse myelitis).

5. Ongoing malignancy or recent diagnosis of malignancy in the last 5 years (excluding basal cell and squamous cell carcinoma of the skin).

6. Tuberculosis or non-tuberculosis mycobacterial infection.

7. Autoimmune disease, including hypothyroidism without a defined nonautoimmune cause.

8. Immunodeficiency of any cause, including from solid organ transplant, blood, or bone marrow transplant, or use of other immune-weakening medicine.

9. Type 1 or 2 diabetes mellitus regardless of disease control.

11. Has any of the following self-reported or medically documented risk factors for severe COVID-19:

1. Chronic kidney disease

2. Cerebrovascular disease

3. Cystic fibrosis

4. Chronic liver disease

5. Pulmonary fibrosis

12. Has participated or plans to participate in another investigational study involving any investigational drug or device within 60 days or 5 half-lives, whichever is longer, before study vaccination and throughout the study.

13. Has received a licensed or authorized non-mRNA COVID-19 vaccine (primary series or booster dose).

14. Has received or plans to receive any licensed vaccine within 4 weeks before or after study vaccination. Inactivated vaccines for influenza are permitted during the study if they are administered at least 14 days before or after study vaccination.

15. Is planning to receive an authorized or licensed COVID-19 booster vaccination for the duration of the study (for participants who are not covered by local recommendations to receive booster per current standard of care) OR is planning to receive an authorized or licensed COVID-19 booster vaccination on or before Day 31 of the study (for participants covered by local recommendations to receive booster).

16. Has received or plans to receive immunoglobulins or any blood or blood products within 90 days before study vaccination and throughout the study.

17. Reports chronic use (more than 14 continuous days) of any medication that may be associated with changes in immune function including, but not limited to, systemic corticosteroids exceeding 20 mg/day of prednisone equivalent, allergy injections, immunoglobulins, interferons, immunomodulators, cytotoxic drugs, or other similar or toxic drugs within 6 months of study vaccination. Note: The use of low-dose topical, ophthalmic, inhaled, intra-articular and intranasal steroid preparations is permitted.

18. Pregnant or lactating female.

19. Female participant planning to become pregnant or planning to discontinue contraceptive precautions within 1 month following study vaccination.

20. Participant is an employee or family member of the investigator or study site personnel.

What this study is about