Immunogenicity and safety of the inactivated enterovirus 71 vaccine administered concomitantly with the measles-rubella vaccine in infants aged 8 months in China: A noninferiority randomized controlled trial.

Background: To evaluate the immunogenicity and safety of simultaneous administration of the enterovirus 71 (EV71) vaccine with the measles and rubella (MR) combined vaccine.

Methods: In this phase 4, randomized, open-label and noninferiority study, a total of 680 infants aged 8 months were enrolled and assigned to the simultaneous administration group (infants received the first dose of EV71 vaccine and MR vaccine on Day 0, and the second dose of EV71 vaccine on Day 28), or the separate administration groups (EV71 group: infants received two doses of EV71 vaccine on Day 0 and Day 28, respectively; MR group: infants received MR vaccine on Day 0). Blood sample was obtained on Day 0 and Day 56 to measure antibody responses to each of the antigens in terms of antibody titer or concentration, respectively. Local and systemic adverse reactions (ARs) and other adverse events (AEs) following each dose were monitored and compared among groups.

Results: After vaccination, simultaneous administration group showed similar seroconversion rates of antibody against EV71(97.9%), measles (97.4%), and rubella (94.3%) compared to EV71 group (99.6% for anti-EV71) or MR group (98.4% for anti-measles and 98.9% for anti-rubella, respectively). Noninferiority was demonstrated for all antibodies as the lower limits of two-sided 97.5% confidence intervals (CIs) of the difference in seroconversion rates between simultaneous administration group and separate administration groups were above the predefined margin of -10%. Additionally, the adverse reaction rates were comparable among groups (54.4% in the simultaneous group versus 43.9% in the MR group versus 52.6% in the EV71 group).

Conclusion: Antibody responses induced by simultaneous administration of EV71 vaccine with MR vaccine were robust and noninferior to those by single administration alone. Like the previous findings by single administration alone, simultaneous administration demonstrated comparable reactogenicity and safety profiles.