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Humoral and cellular immunity of two-dose inactivated COVID-19 vaccination in Chinese children: A prospective cohort
Hao Wang1, Mengze Gan2, Bihao Wu3
1Department of Occupational and Environmental Health and Department of Epidemiology and Biostatistics, Ministry of Education and State Key Laboratory of Environmental Health, Huazhong University of Science and Technology, Wuhan, China.
Insights
Two doses of inactivated COVID-19 vaccine significantly boost antibody and cellular immunity in children. This provides evidence for an effective vaccination strategy against the pandemic in pediatric populations.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Children represent a high-risk demographic for COVID-19, necessitating vaccination.
- The immune responses following COVID-19 vaccination in children require further elucidation.
- Optimal immunization strategies for inactivated COVID-19 vaccines in pediatric populations are under investigation.
Purpose of the Study:
- To evaluate the immunogenicity of one versus two doses of an inactivated COVID-19 vaccine in children.
- To establish a rational immunization strategy for inactivated COVID-19 vaccines in the pediatric population.
Main Methods:
- A prospective cohort study involving 322 children who received an inactivated COVID-19 vaccine.
- Assessment of receptor binding domain (RBD)-IgG and neutralizing antibody (NAb) titers post-first and post-second vaccination.
- Flow cytometry analysis to evaluate SARS-CoV-2 specific cellular immunity, including T cell responses and memory T cell generation.
Main Results:
- The second vaccine dose significantly increased median titers of RBD-IgG and NAb against prototype and Omicron strains compared to the first dose (p < 0.05).
- The first vaccine dose induced SARS-CoV-2 specific cellular immunity, while the second dose enhanced CD4+ T cell responses, including multifunctional T cells.
- SARS-CoV-2 specific memory T cells, including central and effector memory T cells, were generated after the first vaccination.
Conclusions:
- Two doses of the inactivated COVID-19 vaccine elicit robust humoral and cellular immune responses in children.
- The findings support the use of a two-dose inactivated vaccine regimen for children to combat the COVID-19 pandemic.
- This study provides crucial scientific evidence for optimizing pediatric vaccination strategies against COVID-19.
Abstract:
Children are the high-risk group for COVID-19, and in need of vaccination. However, humoral and cellular immune responses of COVID-19 vaccine remain unclear in vaccinated children. To establish the rational immunization strategy of inactivated COVID-19 vaccine for children, the immunogenicity of either one dose or two doses of the vaccine in children was evaluated. A prospective cohort study of 322 children receiving inactivated COVID-19 vaccine was established in China. The baseline was conducted after 28 days of the first dose, and the follow-up was conducted after 28 days of the second dose. The median titers of receptor binding domain (RBD)-IgG, and neutralizing antibody (NAb) against prototype strain and Omicron variant after the second dose increased significantly compared to those after the first dose (first dose: 70.0, [interquartile range, 30.0-151.0] vs. second dose: 1261.0 [636.0-2060.0] for RBD-IgG; 2.5 [2.5-18.6] vs. 252.0 [138.6-462.1] for NAb against prototype strain; 2.5 [2.5-2.5] vs. 15.0 [7.8-26.5] for NAb against Omicron variant, all p < 0.05). The flow cytometry results showed that the first dose elicited SARS-CoV-2 specific cellular immunity, while the second dose strengthened SARS-CoV-2 specific IL-2+ or TNF-α+ monofunctional, IFN-γ+ TNF-α+ bifunctional, and IFN-γ- IL-2+ TNF-α+ multifunctional CD4+ T cell responses (p < 0.05). Moreover, SARS-CoV-2 specific memory T cells were generated after the first vaccination, including the central memory T cells and effector memory T cells. The present findings provide scientific evidence for the vaccination strategy of the inactive vaccines among children against COVID-19 pandemic.
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