Immunogenicity and safety profiles of a new MAV/06 strain varicella vaccine in healthy children: A multinational, multicenter, randomized, double-blinded, active-controlled phase III study.

Immunization is the most effective preventive strategy against varicella. While the Oka strain is commonly used for varicella vaccination worldwide, Korea widely uses the MAV/06 strain. A new live attenuated MAV/06 strain varicella vaccine (MG1111), which uses the new cell line Medical Research Council-5 for better viral propagation, was developed. MG1111 was approved by Korean health authorities. Here, we report the results of phase III, randomized, double-blind, multicenter study conducted in Korea and Thailand, which compared the immunogenicity and safety profiles of MG1111 versus the control vaccine, Varivax. In total, 515 healthy children (12 month-12 years) were randomized 1:1 to receive either the MG1111 or control vaccine (MG1111: 258, Control: 257). The seroconversion rate (SCR) and geometric mean titer (GMT) were measured using the fluorescent antibody to membrane antigen (FAMA) test. The MG1111 group achieved a SCR of 97.9% (95% CI: 95.2-99.3) after vaccination. The lower limit of 95% CI for SCR difference (MG1111-Varivax) was -4.0%, which was higher than the specified non-inferiority margin of -10%. Further, the GMT of the MG1111 increased from 2.0 to 74.2 (95% CI: 65.0-84.8) and the lower limits of the 95% CI for post-vaccination GMT ratios (MG1111/Varivax) were 0.55 higher than the specified parameter of 0.5. Therefore, the MG1111 group was not statistically inferior to the control vaccine group in terms of SCR and GMT. Furthermore, the MG1111 and control vaccine groups were not significantly different in the percentage of participants showing adverse events-solicited, local, or systemic during 43-day period of observation and serious adverse events during 6 month of observation. The present results indicate that MG1111was not immunologically inferior to Varivax, and safety profiles of MG1111 are similar to those of Varivax.