Pneumococcal conjugate vaccines decrease community-acquired alveolar pneumonia with and without pleural effusion in children <60 months in Southern Israel, 2002–2016

Background: Radiographically-proven community-acquired alveolar pneumonia with pleural effusion (PE-CAP) has a less favourable outcome than pneumonia without pleural effusion (NPE-CAP). We assessed PE-CAP and NPE-CAP rate dynamics in children <60 months in southern Israel before and after 7- and 13-valent pneumococcal conjugate vaccine (PCV7/PCV13) implementation (2002–2016). Methods: An ongoing, prospective observational study. Our hospital serves a captive population of ∼75,000 children <60 months, enabling incidence calculation. PCV7/PCV13 were implemented in Israel in July 2009/November 2010, respectively. All chest radiographs (CXRs) were digitalized and analysed according to the WHO Standardization of Interpretation. Annual incidences of PE-CAP and NPE-CAP were calculated, 2002–2016. Incidence-rate ratios (IRRs) comparing PCV13 (2013–2016), PCV7 (2010–2011) and pre-PCV (2002–2008) periods were calculated. Results: Overall, 12,271 CAP episodes were identified; 159 (1.3%) PE-CAP and 12,112 (98.7%) NPE-CAP. In total, 65.8% and 34.2% were children <24 and 24–59 months, respectively; 61.0% and 39.0% were Bedouin and Jewish children, respectively. Following PCV7 introduction, PE-CAP rates declined by 48% (Incidence rate ratios [IRR] = 0.52; 0.26–1.03), while NPE-CAP rates declined by 20% (IRR = 0.80; 0.75–0.86). In the PCV13 period, PE-CAP and NPE-CAP rates further declined, resulting in overall 70% (IRR = 0.30; 0.18–0.50) and 55% (IRR = 0.45; 0.43–0.48) reductions, respectively, comparing the PCV13 and the pre-PCV periods. Similar trends were observed in all subgroups (Bedouin vs. Jewish and age < 24 months vs. 24–59 months). Conclusions: Following PCV7/PCV13 introduction, PE-CAP and NPE-CAP rates substantially declined. However, the rate dynamics were different, with steeper declines observed in PE-CAP rates, possibly deriving from differences in disease aetiology.