Decline in Community-Acquired Alveolar Pneumonia Positive for Respiratory Syncytial Virus in Hospitalized Children Following Implementation of Pneumococcal Conjugate Vaccine (PCV) in Israel

Abstract

BACKGROUND We assessed the impact of pneumococcal conjugate vaccine (PCV) implementation on respiratory syncytial virus-positive community-acquired alveolar pneumonia (RSV-CAAP) in young children in southern Israel. METHODS This study was nested within a prospective population-based active surveillance system during 2004-2019. All children <60 months residing in the region and served by the region's only hospital were included. A negative binomial regression model was used to evaluate the impact of PCV on the incidence of all-cause CAAP and RSV-CAAP and was the basis for estimating averted episodes. RESULTS 7,640 all-cause CAAP episodes were observed; 50% were tested for RSV, of which 42% were positive. Shortly after PCV13 implementation, all-cause CAAP and RSV-CAAP rates markedly declined, stabilizing within 3-4 years. The mean annual hospitalization rates for all-cause CAAP and RSV-CAAP declined by 47% (95% CI: 40%; 53%) and 29% (95% CI: -2%; 51%), respectively, during the late-PCV period, compared with the expected rates. This translated to a reduction in the mean annual incidence of 3.73 cases of all-cause CAAP/1,000 children (95% CI: 2.98;4.58) and 0.50 cases of RSV-CAAP per 1,000 children (95% CI: -0.05;1.13). The highest incidences of averted cases occurred in children aged 12-23 months. CONCLUSIONS The observed dynamics of hospitalizations due to all-cause CAAP and RSV-CAAP following PCV implementation are consistent with the notion of a synergistic role of RSV and pneumococcus in CAAP in young children.