ELISA antibody titer in time-point serum samples from participants in 100 and 200 µg groups.

Note: A: ELISA antibody titer to the PfCP-2.9 in pre-immune serum samples(Day 0) is <1∶100 B: ELISA antibody titer to the PfCP-2.9 in sera from participants receiving the placebo injection is <1∶100 C. The first vaccination was performed on day 0 and boosted vaccination were on days of 60 and 180 D. ND: not done