Patients with C3 inhibition may have an increased susceptibility to infections and should possibly be immunized against bacterial infections, however there is evidence that a low C3 concentration of less than 20% of the normal range in the circulation is sufficient to maintain adequate activation of complement response in adults with fully developed adaptive immunity (Da Silva et al., 2016; Ricklin et al., 2016). This evidence concerns the gene C3 and bacterial infectious disease.