ABSTRACT
BACKGROUND: This study aimed to determine factors affecting serum levels of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies 2 months after coronavirus disease 2019 (COVID-19) vaccination in young and middle aged healthy adults. MATERIALS AND METHODS: Healthcare workers who have no history of SARS-CoV-2 infection, were enrolled at 2 months after second shot of BNT162b2 mRNA COVID-19 vaccine. Antibody immunoglobulin G against the spike protein subunit of SARS-CoV-2 was semi-quantitatively measured using 4 commercial enzyme-linked immunosorbent assay kits. Factors affecting anti-SARS-CoV-2 antibodies levels were investigated. RESULTS: Fifty-one persons (22 - 54 years, male sex; 19.6%) were enrolled and all participants acquired anti-SARS-CoV-2 antibodies in four diagnostic kits. Anti-SARS-CoV-2 antibodies were strongly correlated between diagnostic kits; SG Medical and Genscript (r = 0.942), SG Medical and HB Healthcare (r = 0.903), and HB Healthcare and Genscript (r = 0.868). We investigated factors affecting antibody level using SG medical kit. The median inhibition was 93.1%, and 84.0% of participants showed >90.0% inhibition. Systemic adverse event severity had no association with the anti-SARS-CoV-2 antibodies level. Antibody level was inversely correlated with weight (-0.312, P = 0.027), body mass index (BMI) (r = -0.303, P = 0.032), and body surface area (r = -0.285, P = 0.044). In multivariate analysis, the upper 50% of anti-SARS-CoV-2 antibodies (≥93.1%) was inversely associated with weight (odds ratio [OR]: 0.19; 95% confidence interval [CI]: 0.04 - 0.83 in weight ≥55kg) and BMI (OR: 0.12; 95% CI: 0.03 - 0.61 in BMI ≥22 kg/m²). CONCLUSION: Anti-SARS-CoV-2 antibody was inversely correlated with weight and BMI, which may be used as a marker to predict immune response of BNT162b2 mRNA vaccination in young and middle aged adults. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05083026.
ABSTRACT
Importance: 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. Objective: 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. Interventions: 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. Results: 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.