Abstract
The implementation of pneumococcal conjugate vaccines (PCVs) has led to a decline in vaccine-type disease. However, there is evidence that the epidemiology of non-typeable Haemophilus influenzae (NTHi) carriage and disease can be altered as a consequence of PCV introduction. We explored the epidemiological shifts in NTHi carriage using whole genome sequencing over a 5-year period that included PCV13 replacement of PCV7 in the UK’s National Immunization Programme in 2010. Between 2008/09 and 2012/13 (October to March), nasopharyngeal swabs were taken from children <5 years of age. Significantly increased carriage post-PCV13 was observed and lineage-specific associations with Streptococcus pneumoniae were seen before but not after PCV13 introduction. NTHi were characterized into 11 discrete, temporally stable lineages, congruent with current knowledge regarding the clonality of NTHi. The increased carriage could not be linked to the expansion of a particular clone and different co-carriage dynamics were seen before PCV13 implementation when NTHi co-carried with vaccine serotype pneumococci. In summary, PCV13 introduction has been shown to have an indirect effect on NTHi epidemiology and there exists both negative and positive, distinct associations between pneumococci and NTHi. This should be considered when evaluating the impacts of pneumococcal vaccine design and policy.
Highlights
Non-typeable Haemophilus influenzae (NTHi) is a Gramnegative bacterium commonly found in the human nasopharynx
Introduction of PCV13 in the UK increased carriage of non-typeable Haemophilus influenzae (NTHi) in children
We explored epidemiological shifts in NTHi carriage over a 5-year period that included PCV13 replacement of PCV7 in the UK’s National Immunisation Programme in 2010
Summary
Non-typeable Haemophilus influenzae (NTHi) is a Gramnegative bacterium commonly found in the human nasopharynx Severe invasive infections such as meningitis and septicaemia caused by capsulated H. influenzae, in particular serotype b (Hib), have been reduced with the widespread use of specific conjugate vaccines [2]. In 12 EU/EEA countries between 2007 and 2014, NTHi accounted for 78 % of the 8781 cases of invasive disease with the burden highest in infants and those !60 years of age [8]. The former increase was largely down to a concerning 6.2 % [95 % confidence interval (CI) 2.8–9.8 %] annual increase in neonatal disease notification [8]
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