Dosing schedule for participants.

Dose 1 of vaccine was given on day 0 in both groups, whereas dose 2 was given either on day 14 or day 28 Dosing schedule for participants.两组受试者均于第0天接种第1剂疫苗，第2剂的接种时间为第14天或第28天。 受试者疫苗接种方案。