Fig. 1

Characteristics and vaccine effectiveness against SARS-CoV-2 Omicron subvariant BA.2 in the children. a Proportion of pediatric and adult patients for Wild-type, Delta, and Omicron BA.2 strains. The red color represents pediatric patients, the blue color represents adult patients and the numbers in the bar represent the total number of patients in each category. b Incubation period of 391 pediatric patients with family clustering in Omicron BA.2 group. The incubation period is the time interval between the date of symptom onset in children and the date their family members first tested positive. c Antibody responses in the pediatric patients infected with Omicron BA.2. The left panel of c represents IgM antibody values (AU/ml) in vaccinated and unvaccinated patients. The right panel of c represents IgG antibody values (AU/ml) in vaccinated and unvaccinated patients. **p < 0.01, ***p < 0.001, Student’s t-test. d IgM and IgG positive rates in vaccinated and unvaccinated patients. Patients are IgM or IgG positive if the IgM or IgG antibody value is greater than 10 AU/ml. *p < 0.05, ***p < 0.001, ns indicates no significance, Student’s t-test. e The time interval from the last dose of vaccination to positive in vaccinated patients with 1 dose and 2 doses. ***p < 0.001, Student’s t-test. f Ct value (ORF1ab and N genes) in patients. The left panel of f represents Ct value (ORF1ab and N genes) on the first day in vaccinated and unvaccinated patients. The right panel of f represents the peak Ct value (ORF1ab and N genes) in vaccinated and unvaccinated patients. ***p < 0.001, Student’s t-test. h The time interval from the positive to negative in vaccinated and unvaccinated patients. ***p < 0.001, ns indicates no significance, Student’s t-test. g The temporal evolution of Ct value (ORF1ab and N genes) of vaccinated and unvaccinated groups. Patients in the unvaccinated and vaccinated groups are selected who turned negative (Ct values of ORF1ab gene and N gene are both greater than 35) and had no subsequent positive return. i Correlation between IgG antibody values and the time for nucleic acid negative conversion (Pearson correlation coefficient, R = −0.28, p < 0.001)