Abstract:Objective To study the clinical features of children with coronavirus disease 2019 (COVID-19) Delta variant infection vaccinated or not vaccinated with inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. Methods A total of 11 children with COVID-19 Delta variant infection who were vaccinated with inactivated SARS-CoV-2 vaccine and were hospitalized in the designated hospital in Henan Province, China, from November 3 to December 17, 2021 were enrolled as the vaccinated group. Thirty-one children with COVID-19 Delta variant infection who were not vaccinated and were hospitalized during the same period were enrolled as the unvaccinated group. A retrospective analysis was performed on their epidemiological data, clinical features, and laboratory examination results. Results There was no significant difference in gender composition and disease classification between the two groups (P>0.05), and there was also no significant difference in the incidence rates of the clinical symptoms such as cough, expectoration, and fever between the two groups (P>0.05). No significant difference was found between the two groups in leukocyte count, lymphocyte percentage, alanine aminotransferase, and serum creatinine (P>0.05). Compared with the unvaccinated group, the vaccinated group had significantly lower levels of aspartate aminotransferase, lactate dehydrogenase, and creatine kinase-MB (P<0.05). There was no significant difference between the two groups in the proportion of children with elevated C-reactive protein or procalcitonin and the levels of peripheral blood cytokines (P>0.05). The vaccinated group had significantly lower counts of B lymphocytes and total T lymphocytes (CD3+) than the unvaccinated group (P<0.05). Compared with the unvaccinated group, the vaccinated group had a significantly higher positive rate of IgG on admission and at week 2 of the course of disease (P<0.05), as well as a significantly higher Ct value of nucleic acid at weeks 1 and 2 of the course of disease (P<0.05). Conclusions Vaccination with inactivated SARS-CoV-2 vaccine may reduce myocardial injury caused by SARS-CoV-2 Delta variant. For children with SARS-CoV-2 Delta variant infection after the vaccination, more attention should be paid to their immune function.
