COVID-19 and Influenza Deaths in Australian Children 2018-2023: A National Case Analysis

Background Understanding COVID-19 and influenza severity in children is essential to inform future public health strategies, including vaccination. We aimed to estimate and compare mortality rates attributable to COVID-19 and influenza in the Australian pediatric population. Methods A case series of children aged <18 years hospitalized with laboratory-confirmed SARS-CoV-2 or influenza and recorded as deceased. COVID-19 cases were ascertained January 2020-September 2023 and influenza, seasonally, from 2018 to September 2023 at 8 sentinel children's hospitals in Australia. Cases were assessed by an expert panel to determine the causal attributability of each virus to death, and those with primary or contributory causal attribution were used to calculate an attributable proportion. Population mortality rates were calculated using all deaths notified to Australia's National Notifiable Diseases Surveillance System (NNDSS). Adjusted mortality rates were estimated using the sample attributable proportions. Results In children who died with SARS-CoV-2 or influenza infection, attributable in-hospital mortality proportions were 11/19 (58%) and 23/29 (79%), respectively. Among COVID-19 and influenza attributable deaths, 47% (16/34) had no known pre-existing comorbidity. The respective crude and adjusted attributable average annualized mortality rates per million population were 1.35 and 0.78 (plausible range: 0.51-1.13) for COVID-19, and 1.34 and 1.06 (0.73-1.15) for influenza. Conclusions In Australia, crude mortality estimates of COVID-19 and influenza in children may include deaths not attributable to the viruses and so overestimate severity. Accurate age-specific attributable mortality rates and their association with medical comorbidity are important for informing vaccination policies and other public health measures for prevention of high-burden respiratory viruses in children.