Please assess the completion status of the following clinical trial:

Trial Title: A Study to Evaluate Safety and Effectiveness of mRNA-1273 COVID-19 Vaccine in Healthy Children Between 6 Months of Age and Less Than 12 Years of Age

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE2/PHASE3
- Number of Arms: 2.0

Eligibility Criteria:
Key Inclusion Criteria:~* For participants with chronic diseases (such as, asthma, diabetes mellitus, cystic fibrosis, human immunodeficiency virus \[HIV\] infection), the disease should be stable, per investigator assessment.~* Investigator assessment that the parent(s)/legally acceptable representatives understand and are willing and physically able to comply with protocol mandated follow-up, including all procedures, written informed consent is provided, and participants provide assent.~* For children 2 years of age or older has a body mass index at or above the third percentile according to World Health Organization (WHO) Child Growth Standards at the Screening Visit.~* For children 6 months to \<12 months of age: born at full-term with a minimum birth weight of 2.5 kilograms (kg).~* For female participants of childbearing potential: negative pregnancy test, adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the first injection, agreement to continue adequate contraception or abstinence through 3 months following the second injection (Day 29) and the third dose in Part 3 (Day 149/booster dose Day 1), and not currently breastfeeding.~Key Exclusion Criteria:~* Known history of SARS-CoV-2 infection within 2 weeks prior to administration of vaccine or known close contact with anyone with laboratory-confirmed SARS-CoV-2 infection or COVID-19 within 2 weeks prior to administration of vaccine.~* Prior administration of an investigational or approved CoV (such as, SARS-CoV-2, SARS CoV, Middle East Respiratory Syndrome CoV) vaccine.~* Treatment with investigational or approved agents for prophylaxis against COVID 19 (such as, receipt of SARS-CoV-2 monoclonal antibodies) within 6 months prior to enrollment.~* Known hypersensitivity to a component of the vaccine or its excipients.~* A medical or psychiatric condition that, according to the investigator's judgment, may pose additional risk as a result of participation, interfere with safety assessments, or interfere with interpretation of results.~* History of a diagnosis or condition that, in the judgment of the investigator, may affect study endpoint assessment or compromise participant safety.~* Received any non-study vaccine within 14 days before or after any dose of vaccine (except for seasonal influenza vaccine, which is not permitted within 14 days before or after any dose of vaccine)~* Received intravenous or subcutaneous blood products (red blood cells, platelets, immunoglobulins) within 3 months prior to Day 1~* Participated in an interventional clinical study within 28 days prior to Day 0 or plans to donate blood products while participating in this study.

- Gender: ALL
- Minimum Age: 6 Months
- Maximum Age: 11 Years
- Healthy Volunteers: t

Study Arms:
- mRNA-1273 (Type: EXPERIMENTAL): Part 1: Participants will receive 2 IM injections of mRNA-1273 at doses pre-specified for this study, on Days 1 and 29. Participants will be offered an optional BD of mRNA-1273 lower than the dose chosen for primary series, ≥6 months after Dose 2. After protocol amendment (PA) 9, participants who have not yet received a BD will be offered a BD with mRNA-1273.214.~Part 2: Participants will receive 2 IM injections of mRNA-1273 at dose selected from Part 1 on Days 1 and 29. Participants (6 to \<12 year) will be offered an optional BD of mRNA-1273 lower than the dose chosen for primary series, ≥6 months after Dose 2. After PA 9, participants who have not yet received a BD will be offered a BD with mRNA-1273.214.~Part 3: Participants will receive 2 IM injections of mRNA-1273 on Days 1 and 29 as primary series then 1 IM injection as Dose 3, on Day 149 ≥3 months and ≤5 months after receipt of Dose 2 of primary series. All 3 injections will be administered at lower dose than that of Part 1.
- Placebo (Type: PLACEBO_COMPARATOR): Part 2 only: Participants will receive 2 IM injections of mRNA-1273-matching placebo on Day 1 and Day 29. Participants (6 to \<12 year old) will be offered an optional BD of mRNA-1273 at a dose lower than the dose that was chosen for the primary series for this age group, at least 6 months post-cross-over Dose 2. After PA 9, participants who have not yet received a BD will be offered a BD with mRNA-1273.214.

Based on this trial design, predict the completion outcome and termination type (if applicable).