Impact of the COVID-19 Pandemic on Under-Five Mortality: An Interrupted Time Series Analysis in Southern Iran

Introduction: The COVID-19 pandemic disrupted healthcare systems globally, potentially impacting the health outcomes of vulnerable populations such as children under five. This study investigated the pandemic’s effect on mortality trends in this age group within a healthcare network under the Shiraz University of Medical Sciences. Methods: In an ecological study, we performed an Interrupted Time Series (ITS) analysis using segmented Poisson regression. We compared the monthly count of deaths among children under five years old for 11 months before and 11 months after the onset of the COVID-19 pandemic (March 2020). Data were extracted from the integrated electronic health record (SIB system) of the Shiraz University of Medical Sciences, covering 32 cities. Results: For infants under one month of age, there was a significant immediate increase in mortality at the onset of the pandemic (β₂ = 2.16, P < 0.001), followed by a significant post-pandemic declining trend (β3 = −0.171, P < 0.001). Among children aged 1 month to 1 year, the pre-pandemic trend was not significant, and neither the immediate level change nor the post-intervention trend was statistically significant. For children under five years, there was a non-significant pre-pandemic trend, a significant immediate increase in mortality at pandemic onset (β₂ = 1.23, P < 0.001), and a significant post-pandemic decreasing trend (β₃ = −0.108, P < 0.001). Conclusion: The COVID-19 pandemic had a dual-phase impact on under-five mortality in the studied population: an initial surge likely linked to healthcare disruptions, followed by a reversal into a decreasing trend, possibly attributable to reduced transmission of common infectious diseases and accidents. This pattern underscores the complex and indirect effects of a global health crisis on child survival.