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Newly Released Latex-Enhanced Immunoturbidimetric Raw Materials Adds to COVID-19 NAb Test Solution
Release Time:23 March.2021

Fapon Biotech new reagent raw materials and test components for the latex-enhanced immunoturbidimetric platform is now added to the COVID-19/SARS-CoV-2 Neutralizing Antibody Test Solution. Products for ELISA, CLIA and CMIA, had introduced earlier in supporting customers’ NAb test development and vaccine effectiveness evaluation. With the company mission, ‘Enable Earlier Disease Identification, More Convenient, Accurate and Affordable Diagnosis’, continues to illuminate each action made during the pandemic, Fapon Biotech seeks ongoing innovations to support pandemic diagnosis and control.

Current Challenge in Vaccine Effectiveness Evaluation

Proverbially, COVID-19 vaccines are a crucial tool to control the global epidemic and restore the economy. After vaccination, neutralizing antibodies (NAbs) will develop as an immune response to fight off the invading SARS-CoV-2 pathogen. Hence to evaluate the effectiveness of a vaccine, it is essential to identify the presence and quantitative level of NAbs, ensuring the titer level needed are reached to fight against future virus encounters.

The current gold standard method uses the live virus neutralization model for NAb detection in vaccine clinical trials, which requires BSL3 laboratory cultivation and can not be applied as a large-scale conventional testing method. Although a BSL3 laboratory does not require in alternative methods pseudovirus-based and GFP/Luciferase gene reporter system, the detection time that takes 3 to 5 days also sets the limit on their application as large-scale conventional tests.

Fapon Biotech COVID-19 NAb Test Solution

Fapon Biotech COVID-19 NAb Test Solution provides alternative testing methods to gold standard live virus-based PRNT with high correlation in performances, solving the problems of requiring high laboratory safety level, long detection time and quantification. Similar products are launched previously for the application of ELISA, CLIA and CMIA platforms (http://bit.ly/3d0QIBb). New products for Latex-Enhanced Immunotrurbidimetry platform are further introduced to diversify the Fapon Biotech COVID-19 NAb Test Solution, offering more options to develop high-throughput, accurate and convenient NAb commercial test kits.

Fapon Biotech COVID-19 NAb Test Solution for Latex-Enhanced Immunoturbidimetry

1. Innovative patented methodology for both neutralizing antibody and total antibody detection

2. Quantitative analysis and dynamic monitoring of vaccine antibody titer and effect evaluation

3. Less detection time, no P3 lab required, break the limitations of testing requirement on environment and personnel

4. Achieve high-throughput detection, meet the needs of different application scenarios

5. High versatility to meet applications in automatic/semi-automatic biochemical instruments, specific protein analyzers, blood-cell counters and other detection platforms

Product Information

Cat. No

Product Name

Product Form



Applicable Analyzer


COVID-19 NAb & Total Ab Test Kit



15:135:15:50; 700nm

Automatic Biochemical Instruments



C1-C6 (FPZ0570)




L/H (FPZ0570)







Sample size

R1 (buffer)

R2 (RBD latex reagent)

R3 (ACE2 latex reagent)


Testing method


Automated Biochemistry Analyzer

Human serum








Specificity & Cut-off Value

The cut-off values for NAb and Total Ab are ≤10AU/mL. Tested 528 random samples, the specificity for NAb and Total Ab is 98.48% and 97.92%

Linearity & Hook Curve

For NAb, the linear range is within 4-160 AU/mL, the linear correlation coefficient is r > 0.990, the absolute deviation is ≤ ±1AU/mL in the range of 4-10 AU/mL, and the relative deviation is ≤ 10% in the range of 10-160 AU/mL

For Total Ab, the linear range is within 2-70 AU/mL, the linear correlation coefficient is r > 0.990, the absolute deviation is ≤ ±6AU/mL in the range of 2-6 AU/mL, and the relative deviation is ≤ 10% in the range of 6-70 AU/mL

Clinical Correlation

The Correlation between Fapon NAb immunoturbidimetry and FDA EUA approved competitive enzyme-linked immunoassay is R = 0.73

The Correlation between Fapon Total Ab immunoturbidimetry and CLIA indirect IgG is R = 0.86


The sensitivity of NAb and Total Ab is LOQ=4 AU/mL and LOQ=1.076 AU/mL


The precision of NAb and Total Ab is CV ≤ 6%


No cross-reaction was shown in mycoplasma pneumonia (n=32) and influenza A (n=7) positive samples