1 Exploring the Clinical Aspects of Vaccine-Preventable Invasive and Non-Invasive Bacterial Disease Within Europe

Abstract

Bacterial infections remain the most common cause of mortality and morbidity in children worldwide. Implementation of vaccination programmes has decreased the incidence of bacterial disease caused by Haemophilus influenzae type b1 and group C meningococci;2 however, invasive disease and mucosal respiratory tract infections due to Gram-positive bacteria, primarily Streptococcus pneumoniae, remain prevalent.3 Pneumonia remains a leading cause of morbidity and mortality in Europe, causing an estimated 300,000 hospitalisations and 31,500 child deaths annually.4 S. pneumoniae causes invasive pneumococcal disease (IPD), characterised by bacteraemia, septicaemia and bacterial meningitis. The consequences can be severe, resulting in hospitalisation, complications and death. Whilst non-invasive diseases are generally less severe than IPD, their higher incidence poses a significant healthcare and social burden, including promotion of antibiotic resistance.5 The introduction of pneumococcal conjugate vaccines has led to important decreases in the incidence of IPD,6 and to a lesser extent on pneumonia hospitalisations7 and on acute otitis media (AOM) visits.8 Although non-typeable H. influenzae (NTHi) has been increasingly recognised as a pathogen in invasive diseases,9 it is also a causative agent of mucosal disease, predominantly in association with S. pneumoniae. The role of NTHi is well established in AOM,10 still controversial in lobar pneumonia, and increasingly implicated in chronic bronchial inflammation in young children with persistent wheezing.11 In Europe, the spectrum of invasive and non-invasive disease that could be prevented by vaccination remains significant, with potential immediate effects on morbidity and mortality, and long-term impact on indirect disease burden.