Please assess the completion status of the following clinical trial:

Trial Title: Study of AZD1222 for the Prevention of COVID-19 in Japan

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE1/PHASE2
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~* Participants aged 18 to 55 years (Cohort A and C), aged 56 to 69 years (Subcohorts B1 and D1), or aged ≥ 70 years (Subcohorts B2 and D2)~Exclusion Criteria:~1. Known past laboratory-confirmed SARS-CoV-2 infection~2. Positive SARS-CoV-2 RT PCR test at screening~3. Seropositivity to SARS-CoV-2 at screening.~4. Significant infection or other illness, including fever \> 37.8°C on the day prior to or day randomization~5. History of Guillain-Barré syndrome~6. Any confirmed or suspected immunosuppressive or immunodeficient state; asplenia; recurrent severe infections and use of immunosuppressant medication within the past 6 months, except topical steroids or short-term oral steroids (course lasting ≤ 14 days)~7. History of allergy to any component of the vaccine~8. Any history of angioedema~9. Any history of anaphylaxis~10. Current diagnosis of or treatment for cancer (except basal cell carcinoma of the skin and uterine cervical carcinoma in situ)~11. History of serious psychiatric condition likely to affect participation in the study~12. Bleeding disorder (eg, factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following IM injections or venepuncture~13. Suspected or known current alcohol or drug dependency~14. Any other significant disease, disorder or finding which may significantly increase the risk to the participant because of participation in the study, affect the ability of the participant to participate in the study or impair interpretation of the study data~15. Severe and/or uncontrolled cardiovascular disease, respiratory disease, gastrointestinal disease, liver disease, renal disease, endocrine disorder and neurological illness (mild/moderate well controlled comorbidities are allowed)

- Gender: ALL
- Minimum Age: 18 Years
- Maximum Age: None
- Healthy Volunteers: t

Study Arms:
- Part I (Type: ACTIVE_COMPARATOR): Cohort C will include healthy participants aged 18 to 55 years. Cohort D will include healthy elderly participants aged ≥ 56 years. In Cohort D, the elderly population is further divided into 2 different age subgroups; aged 56 to 69 years (Subcohort D1) and aged ≥ 70 years (Subcohort D2). At least 30% of participants in Cohort D will be secured for participants with age ≥ 70 years.
- Part II (Type: PLACEBO_COMPARATOR): Cohort C will include healthy participants aged 18 to 55 years. Cohort D will include healthy elderly participants aged ≥ 56 years. In Cohort D, the elderly population is further divided into 2 different age subgroups; aged 56 to 69 years (Subcohort D1) and aged ≥ 70 years (Subcohort D2). At least 30% of participants in Cohort D will be secured for participants with age ≥ 70 years.

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