The purpose of this study is to assess the safety and immunogenicity of MVC-COV1901 vaccine compared to placebo in participants aged ≥ 12 to < 18 years.

This is a Phase II, prospective, placebo-controlled, double-blinded (investigator/site staff and participants), multi-center study; the Sponsor will be blinded until the interim analysis. Participants aged ≥ 12 to < 18 years will be enrolled. All eligible participants will be randomized to receive either MVC-COV1901 or placebo in a 6:1 ratio.

Inclusion Criteria:

• Male or female participant ≥ 12 to < 18 years of age at randomization.

• Body mass index (BMI) at or above the third percentile according to World Health Organization (WHO) BMI-for-age at the Screening Visit.

• Female participant must:

  1. Be either of non-childbearing potential, i.e. surgically sterilized (defined as having undergone hysterectomy and/or bilateral oophorectomy and/or bilateral salpingectomy; tubal ligation alone is not considered sufficient);
  2. Or, if of childbearing potential, be abstinent or agree to use medically effective contraception from 14 days before screening to 30 days following the last injection of study intervention. Acceptable forms include:

  i. Implanted hormonal methods of contraception or placement of an intrauterine device or intrauterine system ii. Established use of hormonal methods (injectable, pill, patch or ring) combined with barrier methods of contraception: condom or occlusive cap (diaphragm or cervical/vault caps) with spermicidal foam/gel/film/cream/suppository

• Has a negative pregnancy test

• Participant is willing and able to comply with all required study visits and follow-up required by this protocol.

• Participant has not travelled overseas within 14 days of screening and will not have any oversea traveling throughout the study period.

• Participant and the participant's legal representative must understand the procedures of the study and provide written informed consent.

Exclusion Criteria:

• Pregnant or breast feeding or have plan to become pregnant in 30 days after last administration of study intervention.
• Currently receiving or received any investigational intervention within 30 days prior to the first dose of study intervention.
• Participant previously received a coronavirus vaccine.
• Administered any licensed live-attenuated vaccines within 28 days or other licensed non-live-attenuated vaccines within 7 days prior to the first dose of study intervention.
• Administered any blood product or intravenous immunoglobulin administration within 12 weeks prior to the first dose of study intervention.
• Currently receiving or anticipate to receive concomitant immunosuppressive or immune-modifying therapy (excluding inhaled, topical skin and/or eye drop-containing corticosteroids, low-dose methotrexate, or < 2 weeks of daily receipt of prednisone less than 20 mg or equivalent) within 12 weeks prior to the first dose of study intervention.
• Currently receiving or anticipate to receive treatment with tumor necrosis factor (TNF)-α inhibitors, e.g. infliximab, adalimumab, etanercept within 12 weeks prior to the first dose of study intervention.
• Major surgery or any radiation therapy within 12 weeks prior to the first dose of study intervention
• Immunosuppressive illness or immunodeficient state, including hematologic malignancy, history of solid organ, bone marrow transplantation, or asplenia.
• Personal or family (linear or collateral relatives by blood within two generations) history of Guillain-Barré syndrome.
• A history of malignancy with potential risk for recurrence after curative treatment, or current diagnosis of or treatment for cancer (exceptions are squamous and basal cell carcinomas of the skin and treated uterine cervical carcinoma in situ, at the discretion of the investigator).
• Bleeding disorder considered a contraindication to intramuscular injection or phlebotomy.
• Participant with ongoing acute diseases or serious medical conditions which will interfere with adherence to study requirements, or the evaluation of any study endpoint. Acute diseases or serious medical conditions include cardiovascular, pulmonary, hepatic, neurologic, metabolic, renal, psychiatric condition (e.g. alcoholism, drug abuse, anorexia or severe depression), current severe infections, autoimmune disease, medical history, physical findings, or laboratory abnormality that in the investigators' opinion are not in stable condition and participating in the study could adversely affect the safety of the participant.
• Participant with previous known SARS-CoV-1 or 2 infection.
• Participant with a history of hypersensitivity to any vaccine or a history of allergic disease or reactions likely to be exacerbated by any component of the MVC-COV1901.
• Body (oral, rectal, or ear) temperature ≥ 38.0°C or acute illness (not including minor illnesses such as diarrhea or mild upper respiratory tract infection at the discretion of the investigator) within 2 days before the first dose of study intervention.