The relationship between SARS-CoV-2 vaccination and COVID-19 in children

ABSTRACT

Objective: To analyze the vaccination status of SARS-CoV-2 in children, and explore the relationship between SARS-CoV-2 vaccination and COVID-19 in children. Methods: A retrospective study was conducted to analyze the clinical data of 335 cases of SARS-CoV-2 Omicron variant infection from February 15, 2022 to March 18, 2022 in Shenzhen Third People's Hospital. Results: Among 335 children with SARS-CoV-2 infection, 174(51.9%) cases were vaccinated with the SARS-CoV-2 vaccine;33(31.4%) cases were vaccinated in the 3-<6 years old group;141(61.3%) cases were vaccinated in the 6-<14 years old group. There was a statistically significant difference in the proportion of SARS-CoV-2 vaccination between the 6-<14 years old group and the 3-<6 years old group (X2=26.1, P < 0.05). In the study cohort, 3-<6 years old group and 6-<14 years old group, there was no significant difference in the incidence of COVID-19 in the vaccinated group compared with the unvaccinated group (P > 0.05). In the study cohort, the proportion of confirmed cases of 1 dose of SARS-CoV-2 vaccine and 2 doses or more of SARS-CoV-2 vaccine was 89.5% (68 cases) and 77.6% (76 cases), respectively;in the 6~<14 years old group, the proportion of confirmed cases of 1 dose of SARS-CoV-2 vaccine and 2 doses or more of SARS-CoV-2 vaccine was 90.0% (54 cases) and 76.5% (62 cases), respectively;the differences were statistically significant (X2=4.264, P < 0.05;X2=4.279, P < 0.05). The IgG levels of 18.28 (6.61, 55.2) AU/mL and 58.3 (25.85, 131.41) AU/mL in the study cohort who were vaccinated for 1 dose, 2 doses and more, respectively;the IgG levels of 20.13 (8.33, 44.33) AU/mL and 56.57 (25.85, 150.07) AU/mL in the 6~<14 years old group who were vaccinated for 1 dose, 2 doses and more, respectively;and the differences were statistically significant (Z=-4.37, P < 0.05;Z=-3.96, P < 0.05). Conclusions: Children who received 2 doses of SARS-CoV-2 vaccine have a lower incidence of COVID-19 and higher levels of SARS-CoV-2 antibodies compared with who received 1 dose. It is recommended that children are advised to be vaccinated against the COVID-19.