Pediatric humoral immune responses and infection risk after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and two-dose vaccination during SARS-CoV-2 omicron BA.5 and BN.1 variants predominance in South Korea

• Published in: Frontiers in immunology Vol. 14; p. 1306604
• Main Authors: Choi, Hyun-Woo, Achangwa, Chiara, Park, Joonhong, Lee, Sun Min, Lee, Nan Young, Jeon, Chae-Hyeon, Choi, Jeong-Hwa, Do, Hyun Kyung, Nam, Jeong-Hyun, Lee, June-Woo, Kim, Byoungguk, Ryu, Sukhyun, Kee, Seung-Jung
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 20.12.2023
• Subjects: antibody response; child; COVID-19; hybrid immunity; Immunology; SARS-CoV-2; vaccine; COVID-19; SARS-CoV-2; vaccine; antibody response; hybrid immunity; child
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2023.1306604

Humoral immune responses and infection risk after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) vaccination during the Omicron BA.5 and BN.1 variants predominant period remains unexplored in pediatric population. We examined anti-spike (anti-S) immunoglobulin G (IgG) responses in a total of 986 children aged 4-18 years who visited outpatient clinics between June 2022 and January 2023, with a history of SARS-CoV-2 infection alone, completed two doses of COVID-19 vaccination alone, vaccine-breakthrough infection (i.e., infection after the single dose of vaccination), and no antigenic exposure. Furthermore, to determine SARS-CoV-2 infection risk, the incidence of newly developed SARS-CoV-2 infection was investigated up to March 2023. The anti-S IgG levels in the 'vaccine-breakthrough infection' group exceeded those in the 'infection alone' and 'vaccination alone' groups (both 0.01). Furthermore, the 'vaccination alone' group experienced more rapid anti-S IgG waning than the 'infection alone' and 'vaccine-breakthrough infection' groups (both 0.01). We could not identify newly developed SARS-CoV-2 infection in the 'vaccine-breakthrough infection' group. Our findings suggest that hybrid immunity, acquired from SARS-CoV-2 infection and COVID-19 vaccination, was a potentially higher and longer-lasting humoral immune response and protected against SARS-CoV-2 infection in pediatric population during Omicron BA.5 and BN.1 variants predominant.