Nontypeable Haemophilus influenzae (NTHi) is increasingly recognized as emerging pathogen. The routine immunization of infants with conjugated
vaccines against H. influenzae type b (Hib) has greatly reduced the incidence of invasive Hib disease; however a marked change in the predominant invasive serotype from Hib to NTHi has occurred. Localized
infections where the role of H. influenzae is important, such as
otitis media in children and acute exacerbations in
chronic obstructive pulmonary disease (
COPD) in adults, are almost exclusively associated with NTHi isolates. The implementation of pneumococcal
conjugate vaccines has resulted in changes in frequency of nasopharynx colonizing pathogens with an increase of NTHi, although this data is yet under debate. An effective
vaccine against NTHi is not currently available. The major challenge in developing a successful
vaccine is the intrinsic heterogeneity of NTHi. H. influenzae
protein D is used as
carrier protein in the licensed
10-valent pneumococcal conjugate vaccine (
Synflorix, GlaxoSmithKline), but no robust evidences for protective efficacy against NTHi
otitis have been until now obtained. Several other
vaccine candidates are under investigations and we hope that significant advancements in
vaccine development will be achieved in the next future. Genome-based
vaccine strategy might provide an additional useful tool for discovering further
vaccine antigens.