Immunogenicity of the AIK-C measles vaccine in infants aged <9 months in Vietnam

Abstract Measles-associated deaths have been reported in infants 4.21 plaque-forming units (PFU)/0.5 mL produced in Vietnam. Paired serum samples were obtained from 196 subjects. Seropositivity was defined as ≥120 mIU/mL. The seroresponse rate was 173/196 (88.27%, 95% confidence interval (CI): 83.77–92.77%) with geometric mean titer (GMT) of 511 mIU/mL (95% CI: 688–880 mIU/mL), and no significant differences were observed by different age groups. Among 196 paired sera, they were categorized into four groups: 122 subjects