Please assess the completion status of the following clinical trial:

Trial Title: Immunogenicity and Safety of Two Different Commercial EV71 Vaccines

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: NONE
- Phase: PHASE4
- Number of Arms: 4.0

Eligibility Criteria:
Inclusion Criteria:~* Healthy volunteer aged 6-35 months;~* Proven legal identity;~* Guardians of the participants should be capable of understanding the written consent form, and such form should be signed before the infant being included into this study.~Exclusion Criteria:~* Prior vaccination with EV71 vaccine;~* History of hand，foot and mouth disease;~* Allergy to gentamicin; history of allergy to any vaccine or vaccine ingredient, or serious adverse reaction(s) to vaccination, such as urticaria,difficulty in breathing, angioneurotic edema, pain, etc;~* Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc;~* Autoimmune diseases or immunodeficiency/immunosuppression;~* Severe neurological disorders (epilepsy, convulsions or convulsions) or psychosis;~* History of thyroidectomy, absence of spleen, functional absence of spleen, and any circumstances leading to absence of spleen or splenectomy;~* Diagnosed coagulation function abnormal (e.g., coagulation factor deficiency, coagulation disorder, or platelet abnormalities) , or obvious bruising or coagulation disorders;~* Any immunosuppressant, cytotoxic medicine, or inhaled corticosteroids (except corticosteroid spray for treatment of allergic rhinitis or corticosteroid treatment on surface for acute non-complicated dermatitis) in the past 6 months;~* Receipt of any of the following products:~  1. Blood product within 3 months prior to study entry;~ 2. Any live attenuated vaccine within 14 days prior to study entry;~ 3. Any subunit vaccine or inactivated vaccine within 7 days prior to study entry;~ 4. Any other study drugs within 30 days prior to study entry;~* Acute disease or acute stage of chronic disease within 7 days prior to study entry;~* Axillary temperature \> 37.0℃;~* Any other factor that suggesting the volunteer is unsuitable for this study based on the opinions of investigators.

- Gender: ALL
- Minimum Age: 6 Months
- Maximum Age: 35 Months
- Healthy Volunteers: t

Study Arms:
- Single vaccine group A (Type: EXPERIMENTAL): This group receive two doses injection of EV71 inactived vaccines(Vero cells) on Day 0 and 30, and two times of blood sampling on day of 0 and 60 respectively for EV71 neutralizing antibody detection.The vaccine was manufactured by Sinovac Vaccine Technology Co., Ltd.
- Single vaccine group B (Type: EXPERIMENTAL): This group receive two doses injection of EV71 inactived vaccines(human diploid cells)on Day 0 and 30, two times of blood sampling on day of 0 and 60 respectively for EV71 neutralizing antibody detection.The vaccine was manufactured by Institute of Medical Biology Chinese Academy of Medical Sciences.
- Sequential vaccination group A (Type: EXPERIMENTAL): One dose injection of EV71 inactived vaccines(Vero cells) on Day 0，following one dose of EV71 vaccine(EV71 inactived vaccines(human diploid cells), and two times of blood sampling on day of 0 and 60 respectively for EV71 neutralizing antibody detection.
- Sequential vaccination group B (Type: EXPERIMENTAL): One dose injection of EV71 inactived vaccines(human diploid cells)on Day 0，following one does of EV71 vaccine(Sinovac Vaccine Technology Co., Ltd), and two times of blood sampling on day of 0 and 60 respectively for EV71 neutralizing antibody detection.

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