Incidence Rates for Invasive Streptococcus pneumoniae and Haemophilus influenzae Infections in US Military Pediatric Dependents Before and During COVID-19

Background/Objectives: Invasive Streptococcus pneumoniae disease (IPD) and invasive Haemophilus influenzae (IHI) infections cause disease in pediatric patients. The COVID-19 pandemic brought about a change in the rates of common viral illnesses that can lead to superimposed bacterial infections. Methods: A repeated monthly cross-sectional study was performed using inpatient data from the Military Health System Data Repository (MDR) to observe differences in IPD and IHI hospitalization rates before and during the COVID-19 pandemic starting in March 2018 and continuing to February 2023. Our study included a cohort of 1.27 million children under the age of 5 years old. Results: A total of 200 unique cases of IPD and 171 unique cases of IHI were identified. In Year 1 of the pandemic, the hospitalization rates for IHI and IPD decreased. In Year 2, IPD returned to the pre-pandemic baseline, and IHI remained below the baseline. In Year 3, IPD increased above the baseline, and IHI returned to the baseline. Conclusions: These data support the notion that the interventions implemented to reduce the spread of COVID-19, such as hand hygiene and social distancing, likely led to a reduction in the incidence of invasive disease. The subsequent relaxation of these mitigation strategies likely led to a resurgence of IHI and an increase in IPD in our population.