This reflects 1) the much higher sporozoite and liver stage antigen load exposure in the PfSPZ-CVac volunteers (inoculated 8–10 weeks before CHMI)13 compared with continuous naturally occurring infections via female Anopheles mosquito injection in the skin (estimated 10–100 sporozoites)55,56 in semi-immune individuals, and 2) the waning of naturally acquired CSP IgM. This evidence concerns the gene CD40LG and infection.