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Humoral Immune Response to Messenger RNA Coronavirus Disease 2019 Vaccination Among Children Aged 5-11 Years in a
Zoe L Lyski1, Cynthia Porter2, Jennifer L Uhrlaub1
1Immunobiology, College of Medicine-Tucson, University of Arizona, University of Arizona Health Sciences, Tucson, Arizona, USA.
Insights
Higher antibody levels in children vaccinated against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) correlated with a lower risk of post-vaccination infection. This finding supports the importance of robust vaccine-elicited immunity.
Area of Science:
- Immunology
- Vaccinology
- Pediatric Infectious Diseases
Background:
- The PROTECT study is a longitudinal cohort study initiated in July 2021 to assess vaccine effectiveness.
- The study involves weekly testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in four US states.
- A key aim is to examine vaccine-elicited antibody responses against SARS-CoV-2 infections occurring after vaccination.
Purpose of the Study:
- To evaluate the relationship between vaccine-elicited antibody levels and the incidence of post-vaccination SARS-CoV-2 infections in children.
- To analyze antibody responses using various assays against different SARS-CoV-2 strains.
Main Methods:
- Serum samples were collected from children aged 5-11 years, 14-59 days post-second dose of the Pfizer-BioNTech mRNA vaccine.
- Antibody levels were measured using enzyme-linked immunosorbent assays (receptor-binding domain [RBD] and S2) and surrogate neutralization assays.
- Assays were performed against ancestral (WA1) and Omicron (BA.2) SARS-CoV-2 variants, measuring area under the curve (AUC) and end-point titer.
Main Results:
- Uninfected children exhibited significantly higher antibody AUCs against both WA1 and Omicron variants compared to infected children.
- A substantial decrease (8.7-fold) in geometric mean surrogate neutralization titer was observed against Omicron (39.7) compared to WA1 (346.0).
- Increased RBD AUC and end-point titers were associated with a reduced odds of post-vaccination infection, with a 47% reduction per SD increase in RBD AUC and a 69% reduction per 3-fold increase in RBD end titer.
Conclusions:
- Children with higher vaccine-elicited antibody levels demonstrated a lower incidence of post-vaccination SARS-CoV-2 infection.
- The findings underscore the protective role of antibody response magnitude against breakthrough infections in vaccinated children.
Background:
The PROTECT study is a longitudinal cohort study initiated in July 2021 with weekly testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 4 states: Arizona, Florida, exas, and Utah. This study aims to examine vaccine-elicited antibody response against postvaccination SARS-CoV-2 infections.
Methods:
Children aged 5-11 years had serum collected 14-59 days after their second dose of monovalent Pfizer-BioNTech coronavirus disease 2019 messenger RNA vaccine. Vaccine-elicited antibodies were measured using the area under the curve (AUC) and end-point titer using enzyme-linked immunosorbent assay (receptor-binding domain [RBD] and S2) and surrogate neutralization assays against ancestral (WA1) and Omicron (BA.2).
Results:
79 vaccinated participants (33 [41.7%] female; median age, 8.8 years [standard deviation, 1.9 years]), 48 (60.8%) were from Tucson, Arizona; 64 (81.0%) were non-Hispanic white; 63 (80.8%) attended school in person; 68 (86.1%) did not have any chronic conditions; and 47 (59.5%) were infected after vaccination. Uninfected children had higher AUCs against WA1 (P = .009) and Omicron (P = .02). The geometric mean and surrogate neutralization titer above the limit of detection was 346.0 for WA1 and 39.7 for Omicron, an 8.7-fold decrease (P < .001). After adjustment of covariates in the WA1-specific model, we observed a 47% reduction in the odds of postvaccination infection for every standard deviation increase in RBD AUC (aOR, 0.53 [95% confidence interval, .29-.97) and a 69% reduction in the odds of infection for every 3-fold increase in RBD end titer (0.31 [.06-1.57]).
Conclusions:
Children with higher antibody levels experienced a lower incidence of postvaccination SARS-CoV-2 infection.
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