What factors are associated with serum levels of anti–SARS-CoV-2 antibodies after COVID-19 vaccination in healthy young and middle-aged persons at 6 months?
In this cohort study of 50 individuals, anti–SARS-CoV-2–specific antibody levels at 2, 4, and 6 months after COVID-19 vaccination were inversely correlated with body weight. Young and middle-aged healthy adults weighing less than 55 kg maintained a high antibody level 6 months after the second dose of BNT162b2 vaccination.
In this study, the inverse correlation of anti–SARS-CoV-2–specific antibody levels with weight was sustained up to 6 months after vaccination; further studies are needed to clarify the antibody cutoff level to protect individuals from severe infection.
The factors associated with long-term serum levels of anti–SARS-CoV-2 antibodies after COVID-19 vaccination in healthy individuals have rarely been investigated.
To investigate factors associated with anti–SARS-CoV-2 antibody levels.
Design, Setting, and Participants
This prospective cohort study included health care workers at Kyungpook National University Chilgok Hospital (Daegu, Korea) with no history of SARS-CoV-2 infection who received 2 doses of the BNT162b2 mRNA COVID-19 vaccine (Pfizer/BioNTech; first dose, March 17-20, 2021; second dose, April 7-10, 2021). Serum samples were collected at 2, 4, and 6 months after the second injection.
SARS-CoV-2 BNT162b2 mRNA vaccine.
Main Outcomes and Measures
Anti–SARS-CoV-2 specific antibodies were measured using enzyme-linked immunosorbent assay kits up to 6 months after the receipt of 2 doses of the BNT162b2 mRNA COVID-19 vaccine. The main outcome was factors associated with anti–SARS-CoV-2 antibody levels at 6 months.
All 50 participants (mean [SD] age, 34.7 [9.4] years; 10 [20.0%] male; mean [SD] body mass index, 21.8 [5.4]) acquired anti–SARS-CoV-2 antibodies and maintained positive antibody (cutoff ≥30%) up to 6 months. The mean serum antibody level decreased with time (91.9%, 89.3%, and 81.5% at 2, 4, and 6 months, respectively). Serum antibody levels at 6 months were correlated with antibody levels at 2 months (R = 0.944; P < .001). The anti–SARS-CoV-2–specific antibody level was inversely correlated with weight, body mass index, body fat amount, and body weight to height ratio in Spearman correlation analysis. A 1-SD increase in body weight, weight to height ratio, and body mass index was associated with a 4%- to 5%-decrease in anti–SARS-CoV-2 antibodies in multiple linear regression analysis for women. In multivariate analysis for categorized variables, lower serum level of antibody (ie, <81.5%) was associated with weight (weight ≥55 kg: odds ratio, 9.01; 95% CI, 1.44-56.40). The probabilities of less than 70% and less than 80% antibody at 6 months were 0% and 11% in participants weighing less than 55 kg, respectively, but 16% and 42% in participants weighing 55 kg or greater.
Conclusions and Relevance
In this study, the inverse correlation of anti–SARS-CoV-2–specific antibody levels with weight was sustained up to 6 months after vaccination. A booster shot of BNT162b2 mRNA vaccination may be given later than 6 months after the second dose in young and middle-aged healthy persons with low body weight.
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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.
Accepted for Publication: April 4, 2022.
Published: May 19, 2022. doi:10.1001/jamanetworkopen.2022.12996
Open Access: This is an open access article distributed under the terms of the CC-BY-NC-ND License. © 2022 Nam SY et al. JAMA Network Open.
Corresponding Author: Su Youn Nam, MD, PhD, Department of Internal Medicine, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, 807 Hoguk-ro, Buk-gu, Daegu 41404, South Korea (firstname.lastname@example.org).
Author Contributions: Dr Nam had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Nam, Yoo.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Nam, H. S. Lee, Lim, D. W. Lee, Yoo.
Critical revision of the manuscript for important intellectual content: Nam, Jeon, Yoo.
Statistical analysis: Nam.
Obtained funding: Nam.
Administrative, technical, or material support: Nam, H. S. Lee, D. W. Lee.
Supervision: Nam, Jeon, Yoo.
Conflict of Interest Disclosures: None reported.
Funding/Support: This project was supported by SG Medical 2021.
Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
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