To address the unmet medical needs during this COVID-19 pandemic, Fapon once again manifests the strength of R&D capabilities to the world by being one of the leading biotechnology companies to launch the COVID-19 Naturalizing Antibodies Titer Testing Solution for ELISA and CLIA. This solution provides raw materials and quality controls to aid the evaluation of vaccine efficacy, antibody-drug effectiveness, convalescent plasma therapy, and seroepidemiological investigation. 

What is COVID-19 Neutralizing Antibodies

Neutralizing antibodies (NAbs) have significant preventive and therapeutic effects by playing crucial roles in controlling viral infection. NAbs target the viral S protein and block the binding ability of S protein to the human angiotensin-converting enzyme 2 (ACE2) receptor, thus preventing viral entry into host cells.

Clinical Applications

Vaccine Efficacy——The clinical therapeutic effect after vaccination is determined by the titers of NAbs produced by the immune response, hence the detection of NAbs can evaluate the vaccine efficacy. 

Antibody-Drug Effectiveness——NAbs are regarded as important therapeutic agents for COVID-19 treatment. In antibody drug development, results of NAbs detection reflect on the neutralizing abilities against the virus, serving as one of the assessing criteria for drug effectiveness evaluation.

Convalescent Plasma Therapy——Convalescent plasma therapy is an experimental treatment for patients with COVID-19. Because people who recovered from COVID-19 have the antibodies to fight off infections, given them to people with severe COVID-19 can boost their ability to combat the virus. The detection of neutralizing antibody levels can identify the ideal recovered plasma donors and indicate the effectiveness of treatment.

Seroepidemiological Investigation——Suggested by the WHO standardized protocol “Population-based age-stratified seroepidemiological investigation protocol for COVID-19 virus infection”, NAbs tests should ideally be performed if samples are positive or equivocal for either IgM, IgA or IgG. Hence it can be used to determine social immunity and assist seroepidemiological study.

Comparison of Different Test Methods for NAbs

Fapon COVID-19 NAbs Titer Testing Solution features raw materials and quality controls that apply in sVNT, which is less time consuming than other test methods, making it more efficient and suitable for academic research and clinical needs.

Product Features

Excellent in Affinity & Specificity

High Correlation to Gold Standard PRNT

High Correlation to FDA EUA Neutralizing Antibody Test Kit

High Compatibility with Wide Application Range

Product Information

Recommended Paris & Performance

Competitive ELISA

1. Product Information

2. Sensitivity evaluation, the IC50 value of Fapon Biotech monoclonal NAb FPZ0570 is 71.2 ng/mL

3. Comparison with gold standard Plaque Reduction Neutralization Test (PRNT), the result of 6 monoclonal NAb strains showed a high correlation at R²=0.771

4. Comparison with FDA EUA Company G sVNT

A high correlation was shown  in the detection of convalescent patient serum at R²=0.9309

A high correlation was shown in the detection of vaccine A vaccinated specimens at R²=0.7688

5. Clinical Specificity

Used Pair 1 & 2 to test 1840 radom samples, no detection was found within cut off=20%

Competitive CLIA/CMIA

1. Product Information

2. Sensitivity & Linearity

Tested Fapon Biotech NAb FPZ0570，LOB＜0.6 AU/mL，linearity=0.6-150 AU, R²=0.999

*  With no international quality control standard for NAb, the Fapon Biotech NAb FPZ0570 herein used as the reference material

3. Clinical Sensitivity & Specificity

Tested convalescent patient serum (1:10 dilution) with 19/20 detection rate; Tested vaccinated sample (1:3 dilution) with 22/23 detection rate, only found negative result in the sample used total antibody sandwich method; Tested 1026 healthy human samples with 1026/1026 specificity; Tested 14 respiratory samples with no obvious cross-reaction

4. Comparison with gold standard Plaque Reduction Neutralization Test (PRNT), the result showed a high correlation at R²=0.7278

5. Comparison with FDA EUA Company G sVNT

A high correlation was shown in the detection of convalescent patient serum at R²=0.9288

A high correlation was shown in the detection of vaccine A vaccinated specimens at R²=0.9012

Double-Antigen Sandwich CLIA/CMIA

1. Product Information

2. Clinical Sensitivity & Specificity

Tested convalescent patient serum (1:20 dilution) with 20/20 detection rate; Tested vaccinated sample (1:3 dilution) with 22/23 detection rate, the negative result also found in the FDA EUA Company G reagent; Tested 1026 healthy human samples with 1010/1012 specificity; Tested 14 respiratory samples with no obvious cross-reaction

3. Comparison with FDA EUA Company G sVNT

A high correlation was shown in the detection of convalescent patient serum at R²=0.8813

A high correlation was shown in the detection of vaccinated specimens at R²=0.7155

Indirect IgG CLIA/CMIA

1. Product Information

2. Clinical Sensitivity & Specificity

Tested convalescent patient serum (1:10 dilution) with 19/20 detection rate; Tested vaccinated sample with 17/19 detection rate; Tested 1017 healthy human samples with 996/1017 specificity; Tested 14 respiratory samples with no obvious cross-reaction

3. Comparison with FDA EUA Company G sVNT

A high correlation was shown in the detection of convalescent patient serum at R²=0.9112

A high correlation was shown in the detection of vaccinated specimens at R²=0.8302