Decline in Pneumococcal Disease in Young Children during the COVID-19 Pandemic in Israel Associated with Suppression of seasonal Respiratory Viruses, despite Persistent Pneumococcal Carriage: A Prospective Cohort Study

BACKGROUND: The incidence of invasive pneumococcal disease (IPD) declined during the COVID-19 pandemic. Previous studies hypothesized that this was due to reduced pneumococcal transmission resulting from non-pharmaceutical interventions. We used multiple ongoing cohort surveillance projects in children <5 years to test this hypothesis. METHODS: The first SARS-CoV-2 cases were detected in February-2020, resulting in a full lockdown, followed by several partial restrictions. Data from ongoing surveillance projects captured the incidence dynamics of community-acquired alveolar pneumonia (CAAP), non-alveolar lower respiratory infections necessitating chest X-rays (NA-LRI), nasopharyngeal pneumococcal carriage in non-respiratory visits, nasopharyngeal respiratory virus detection (by PCR), and nationwide invasive pneumococcal disease (IPD). Monthly rates (January-2020 through February-2021 vs. mean monthly rates 2016-2019 [expected rates]) adjusted for age and ethnicity, were compared. RESULTS: CAAP and bacteremic pneumococcal pneumonia were strongly reduced (incidence rate ratios, [IRRs] .07 and .19, respectively); NA-LRI and non-pneumonia IPD were also reduced, with a lesser magnitude (IRRs, .46 and .42, respectively). In contrast, pneumococcal carriage prevalence was only slightly reduced, and density of colonization and pneumococcal serotype distributions were similar to previous years. The decline in pneumococcus-associated disease was temporally associated with a full suppression of RSV, influenza viruses, and hMPV, often implicated as co-pathogens with pneumococcus. In contrast, adenovirus, rhinovirus, and parainfluenza activities were within or above expected levels. CONCLUSIONS: Reductions in pneumococcal and pneumococcus-associated diseases occurring during the COVID-19 pandemic in Israel were not predominantly related to reduced pneumococcal carriage and density, but were strongly associated with the disappearance of specific respiratory viruses.