COMPARISON OF DIFFERENCES IN CLINICAL MANIFESTATIONS, LABORATORY FINDINGS AND OUTCOMES BETWEEN PEDIATRIC COVID-19 PATIENTS HOSPITALIZED DURING THE DELTA AND OMICRON PERIODS AT NARESUAN UNIVERSITY HOSPITAL, THAILAND

Little is known about the manifestations and outcomes of coronavirus disease-2019 (COVID-19) by viral variant type among children in Thailand. In this study we aimed to compare the clinical characteristics, laboratory findings and outcomes of pediatric COVID-1 9 patients during the 2 periods when the Delta and Omicron variants were predominating in order to inform efforts to control these infections in the study area. We conducted a retrospective review of the medical records of subjects aged <15 years admitted to Naresuan University Hospital, Thailand during 1 April 2021- 30 November 2022 diagnosed with COVID-19 based on the results of a positive reverse transcriptase polymerase chain reaction (RT-PCR) test. Exclusion criteria for study subjects were not having a COVID-19 RT-PCR result in the chart or not being hospitalized. The minimum sample size calculated to be needed for the study was 390; 65 subjects who contracted COVID-19 when the delta variant predominated (Delta Group) and 325 who contracted COVID-19 when the omicron variant predominated (Omicron Group). A total of 396 subjects were included in the study, 68 (17.2%) in the Delta Group, 38 males (55.9%); and 328 (82.8%) in the Omicron Group, 175 males (53.4%). The median age of Delta Group subjects was 9 years and Omicron Group subjects was 6 years. Factors that were significantly different, respectively, between Delta Group and Omicron Group subjects were: anosmia (10.3% vs 0.3%) (p<0.001), p< 0.001), a fever >38 degrees C (10.3% vs 34.2%) (p< p< 0.001), sore throat (17.6% vs 35.7%) (p= p= 0.004), diarrhea (4.4% vs 15.2%) (p= p= 0.017), vomiting (4.4% vs 23.2%) (p< p< 0.001), presence of lymphopenia (4.4% vs 21.9%) (p<0.001), p< 0.001), C-reactive protein levels (0.6 mg/l vs 2.3 mg/l) ( p< 0.001) and procalcitonin levels (0.05 ng/ml vs 0.12 ng/ml) ( p< 0.001). The subjects in both groups had primarily mild disease, but there was 1 death in the Omicron Group; none in the Delta Group. In summary, anosmia was more common in the Delta Group but high fever, sore throat, vomiting, diarrhea, gastrointestinal symptoms, lymphopenia and elevated inflammatory markers were more common in the Omicron Group. These findings show differences in the clinical presentations and laboratory results among pediatric patients by COVID-1 9 viral variant type. For the most part, subjects from both groups had mild symptoms except for 1 death in the Omicron Group. Further studies are needed to determine if these findings hold true for other institutions.