Clinical characteristics and risk factors of severe COVID-19 in hospitalized neonates with omicron variant infection: a retrospective study

Reports on coronavirus disease 2019 (COVID-19) in neonates are limited, especially in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) Omicron variant. This study aims to analyze the clinical characteristics and identify risk factors associated with severe COVID-19 in neonates infected with Omicron variant. The study population was represented by neonates with COVID-19, who were admitted to The Affiliated Children's Hospital of Xi'an Jiaotong University in northwest China, from December 10, 2022 to January 20, 2023. Chinese Center for Disease Control and Prevention (CDC) announced that all local COVID-19 cases were infected with Omicron variant during the study period. Clinical and laboratory data were collected retrospectively. We used logistic regression analysis to investigate the risk factors for severe COVID-19, and derived odds ratios (ORs) and the corresponding 95% confidence intervals (CIs). A total of 108 neonates, with median age of 18.1 days (interquartile range 9.4-23.0), were affected by COVID-19, of whom 84 had a mild disease, while 24 a severe one (22.2%). Of them, 6.5% were premature. No deaths were observed in the study population. The most common clinical manifestations were fever (88.9%) and cough (55.6%), with 5 cases (4.6%) complicated by pneumonia. 4 cases (3.7%) received respiratory support, including 2 cases of high-flow oxygen and 2 cases of continuous positive airway pressure. Gestational age at birth (OR: 0.615; 95% CI: 0.393-0.961), neutrophil count (NEU) (OR:0.576; 95% CI : 0.344-0.962) and lymphocyte count (LYM) (OR: 0.159; 95% CI: 0.063-0.401) were independent risk factors for severe COVID-19. The combination of NEU and LYM had the largest receiver operating characteristic area under the curve [0.912 (95% CI:0.830-0.993)] for identifying severe COVID-19, with a sensitivity of 0.833 and a specificity of 0.917. The general presentations and outcomes of neonatal COVID-19 caused by Omicron variant were not severe, and very few patients required respiratory support. The simultaneous decrease in NEU and LYM can be used to identify severe infection.