Whilst IgG3 and IgM in V1S1 children decreased post-infection, there was not an accompanying increase in HA-diverse IgG1 or FcγR2a and FcγR3a binding responses but rather a reduction, suggesting that V1S1 children did not become V0S0-like in their responses post-infection and remain unable to fully maximize antibody effector functions. The gene discussed is CD40LG; the disease is infection.