Passive immunization with human anti-protein D antibodies induced by polysaccharide protein D conjugates protects chinchillas against otitis media after intranasal challenge with Haemophilus influenzae

Passive transfer of a pediatric human serum pool generated against polysaccharide-protein D conjugate vaccines conferred ∼34% protection against development of ascending NTHI-induced OM when used in a chinchilla viral–bacterial co-infection model. These data are in line with results obtained using a similar 11-valent-protein D conjugate vaccine in a pediatric clinical trial, wherein a vaccine efficacy of 35.6% was shown against acute OM episodes caused by NTHI. These observations strongly support the chinchilla passive transfer-superinfection model as one that could predict clinical trials outcomes for vaccines to prevent NTHI-induced OM.