Changes in the incidence, viral coinfection pattern and outcomes of pneumococcal hospitalizations during and after the COVID-19 pandemic.

BACKGROUND

The incidence of pneumococcal pneumonia in the context of the Coronavirus Disease 2019 (COVID-19) pandemic, along with the real-world data on the ratio of non-invasive to invasive pneumococcal pneumonia, is an area that has not been thoroughly studied. The outcomes associated with coinfection of influenza and COVID-19 remain unknown. This study examined the incidence, demographics, coinfection with influenza and/or COVID-19, and clinical outcomes of pneumococcal hospitalizations in Hong Kong during the baseline, pandemic, and post-pandemic periods.

METHODS

Hospitalization records of individuals aged 18 years and above with pneumococcal disease from January 2015 to August 2024 were extracted from the territory-wide electronic medical record database. Pneumococcal disease was categorized into invasive pneumococcal pneumonia (IPP), invasive pneumococcal disease without pneumonia (IPDWP), and non-invasive pneumococcal pneumonia (NIPP), followed by univariate and multivariate analyses. Effects of coinfection with influenza and COVID-19 were analyzed.

RESULTS

The incidence of pneumococcal disease decreased during the COVID-19 pandemic but rebounded in the post-pandemic period. There were no significant changes in the distribution of pneumococcal serotypes across the three periods. The study revealed a strong positive correlation between monthly pneumococcal hospitalizations and the indicator of influenza activity, while the correlation with the COVID-19 indicator was weak. Additionally, strong positive correlations were observed between the indicator of influenza activity and influenza coinfections, as well as between the indicator of COVID-19 activity and COVID-19 coinfections. Multivariate analyses identified male gender, a higher comorbidity index, older age, invasive pneumococcal disease (IPP and IPDWP), coinfection with influenza and COVID-19, and hospitalization during the pandemic period as factors associated with adverse outcomes.

CONCLUSIONS

The study showcases changes in the epidemiology of pneumococcal disease during and after the COVID-19 pandemic. It highlights the adverse effects of influenza and COVID-19 coinfections on the outcomes of patients with pneumococcal disease and emphasizes the need to vaccinate vulnerable populations against these infections.