A Randomized Controlled Clinical Trial of Nasal Immunization with Live Virulence Attenuated Strains Using Human Infection Challenge.

Pneumococcal pneumonia remains a global health problem. Pneumococcal colonization increases local and systemic protective immunity, suggesting that nasal administration of live attenuated (Spn) strains could help prevent infections. We used a controlled human infection model to investigate whether nasopharyngeal colonization with attenuated strains protected against recolonization with wild-type (WT) Spn (SpnWT).

RTS,S vaccination is associated with serologic evidence of decreased exposure to Plasmodium falciparum liver- and blood-stage parasites.

The leading malaria vaccine candidate, RTS,S, targets the sporozoite and liver stages of the Plasmodium falciparum life cycle, yet it provides partial protection against disease associated with the subsequent blood stage of infection. Antibodies against the vaccine target, the circumsporozoite protein, have not shown sufficient correlation with risk of clinical malaria to serve as a surrogate for protection. The mechanism by which a vaccine that targets the asymptomatic sporozoite and liver stages protects against disease caused by blood-stage parasites remains unclear.