Consistency analysis (ELISA and pseudoviral neutralization test method), dose‐response relationship (humoral immunity) (Day 14, 28, Month 3, 6 postvaccination), Persistence analysis of anti‐S protein antibodies (Day 14, 28, Month 3, 6 postvaccination), Time‐dose‐response relationship (Humoral immunity) (Day 14, 28, Month 3, 6 postvaccination), Dose‐response relationship (cellular immunity) (Day 14, 28, Month 6 postvaccination), Persistence analysis of cellular immuse (Day 14, 28, Month 6 postvaccination), Time‐dose‐response relationship (cellular immunity) (Day 14, 28, Month 6 postvaccination)