A booster dose of the same vaccine(lot 90-2)was given to 68 cvacinees 1 year after immunization,abruptimmune response was observed in both EL ISA and NT antibodies.

• 对68例接种者于免疫后1年用同一疫苗(90-2批)加强免疫一次,其ELISA及中和抗体均显著升高。