RESUMO
OBJECTIVES: To study the epidemiological and clinical features of children with coronavirus disease 2019 (COVID-19) caused by Delta variant infection and their differences from children with ordinary COVID-19 (non-Delta variant infection). METHODS: Eleven children aged <14 years, who were diagnosed with COVID-19 caused by Delta variant infection from August to September 2021 were enrolled (variant group). Five children aged <14 years who were diagnosed with ordinary COVID-19 from February to March 2020 served as the control group. The epidemiological data, clinical features, and laboratory examination results were compared between the two groups. RESULTS: There was no significant difference in the proportion of children with clinical symptoms between the two groups (P>0.05). There were no significant differences in white blood cell count, lymphocyte count, and platelet count between the two groups (P>0.05), while the variant group had a lower neutrophil count than the control group (P<0.05). Lymphocytopenia was not observed in either group. Compared with the control group, the variant group had a higher proportion of children with an increase in creatine kinase isoenzyme (P<0.05), while there were no significant differences in the proportion of children with an increase in lactate dehydrogenase, D-Dimer, C-reactive protein or interleukin-6 between the two groups (P>0.05). Among the 9 children in the variant group, 5 tested positive for IgM antibody at week 2 after admission, and all children tested positive for IgG antibody. At week 3 after admission, the level of IgM antibody tended to decrease in 9 children, and the level of IgG antibody tended to decrease in 8 children. CONCLUSIONS: Delta variant is more infectious. COVID-19 caused by Delta variant infection may cause more serious myocardial damage than ordinary COVID-19 in children. In children infected with Delta variant, IgG antibody appears at almost the same time as IgM antibody.