Decreased prevalence of Moraxella catarrhalis in addition to Streptococcus pneumoniae in children with upper respiratory tract infection after introduction of conjugated pneumococcal vaccine: a retrospective cohort study

ObjectivesTo study effects of the introduction pneumococcal conjugate vaccines (PCV) on interspecies dynamics Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in preschool children with respiratory tract infection.MethodsNasopharyngeal samples from aged ≤6 years upper infection (n = 14 473) South Sweden were analysed during consecutive years, 5 before 9 after PCV introduction. The yearly prevalence was calculated, multivariate count regressions between estimated proportions vaccinated performed. Associations serotypes other pathogens assessed.ResultsWhen comparing prevaccine period introduction, S. pneumoniae decreased by 65.2% (16.4 to 5.7 per 1000 individuals; p < 0.001), whereas M. H. 52.1% (21.5 10.3 0.001) 46.6% (13.6 7.3 respectively. In negative binomial adjusted for numbers taken, significantly negatively associated increasing vaccine coverage (adjusted ratio (aPR) 0.17; 0.001 aPR 0.48; 0.001, respectively), (aPR 0.75; 0.17) not. addition, proportion cultures positive as well lower postvaccine compared period, while this not case influenzae. A significant association certain simultaneous growth observed.ConclusionsAfter PCV, addition decreased; also adjusting reduced taken. This may partly be attributed a catarrhalis.