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Age dependent discrepancy between SARS-CoV-2 anti-nucleoprotein antibody and anti-RBD spike protein antibody in
Yasuhito Fujii1, Hidetoshi Ishigaki1, Isao Miyairi1
1Department of Pediatrics, Hamamatsu University School of Medicine, Japan.
Insights
Over half of Japanese children studied were infected with SARS-CoV-2 by May 2023. Antibody levels suggest immunization protected children, but this effect waned in early 2023.
Area of Science:
- Pediatric Infectious Diseases
- Immunology
- Epidemiology
Background:
- COVID-19 is prevalent in Japanese children.
- The impact of immunization coverage on SARS-CoV-2 seroprevalence in children remains unclear.
Purpose of the Study:
- To investigate SARS-CoV-2 seroprevalence in hospitalized children in Japan.
- To assess the correlation between antibody levels and immunization status.
Main Methods:
- Studied 586 children aged 0-18 hospitalized between June 2020 and May 2023.
- Measured SARS-CoV-2 anti-nucleoprotein (N) and anti-RBD spike (S) protein antibodies.
Main Results:
- Seroprevalence of anti-S antibodies reached 60% by early 2023; anti-N antibodies reached 50% by May 2023.
- Age-dependent discrepancies in anti-S and anti-N antibody prevalence were observed, correlating with vaccine uptake.
- The protective effect of immunization appeared to diminish after early 2023.
Conclusions:
- Approximately half of the pediatric cohort showed evidence of SARS-CoV-2 infection by May 2023.
- Observed antibody discrepancies highlight the role of vaccination in reducing infection rates.
- Findings suggest a need for continued monitoring of vaccine effectiveness in pediatric populations.
Background:
COVID-19 has become widespread in Japanese children. However, the impact of varying immunization coverage on the seroprevalence of SARS-CoV-2 in children is unknown.
Methods:
We examined the SARS-CoV-2 antibody in children aged 0 to 18 who were hospitalized at a university hospital from June 2020 through May 2023. The SARS-CoV-2 anti-nucleoprotein (N) antibody and anti-RBD spike (S) protein antibody was measured.
Results:
A total of 586 cases were enrolled. The median age was 4 years old (interquartile range 1-9), and 362 (61.8 %) were male. The seroprevalence of anti-S antibodies gradually increased from October 2021 and reached 60 percent by early 2023. The anti-N antibody increased starting in January 2022 and reached 50 percent in May 2023. There was a discrepancy in the seroprevalence of anti-S and N antibodies in children 0 years of age or 12 years and older until the fall of 2022. This discrepancy was minimal for children 1-4 years of age and relatively small in the 5-11-year-old group.
Discussion:
The data suggests that approximately half of the children in our cohort had been infected with SARS-CoV-2 by May 2023. The discrepancy in seropositivity between the anti-S and N antibodies corresponded to the reported vaccine uptake of each target age group, which suggested protective effects of immunization. However, this effect appeared to diminish after early 2023.
Conclusion:
Age dependent discrepancy between SARS-CoV-2 anti-N and anti-S antibody in children reflected differences in vaccine coverage.
