Suppression of vaccine responses by malaria: insignificant or overlooked?

Malaria is widely reported to suppress immune responses to heterologous antigens, including vaccines, but the evidence base for this assumption is patchy and confusing. Here we review the evidence for malaria-mediated suppression of responses to vaccination and conclude that: there is evidence of impairment of responses to heterologous polysaccharide antigens in children with clinical malaria or asymptomatic parasitemia; there is little evidence of impairment of responses to routine, protein-based childhood vaccine regimens; and the underlying mechanisms of impaired responsiveness, and especially of impaired responses to T-independent polysaccharide antigens, remain unclear. We suggest that, with the possible exception of vaccines against encapsulated bacteria, the benefits of postponing vaccination until a malaria infection has cleared are probably outweighed by the risk of missing opportunities to vaccinate hard-to-reach populations.