COVID-19 Neutralising Ab Rapid Test

Published on 02/03/2021

Learn how the test works

COVID-19 Neutralizing Ab Rapid Test

COVID-19 Neutralising Ab Rapid Test is a CE certified rapid device for the qualitative detection of IgG antibodies against SARS-CoV-2 Spike protein in whole blood, serum or plasma specimens. For professional in-vitro use only.

Are you interested in our COVID-19 Neutralising Ab Rapid Test? Please write to for further information.

Principle of the Test

The target analyte of this test, the IgG directed against the RBD portion of the SARS-CoV-2 Spike protein, is captured on the one hand by the specific antigen and, on the other hand, by an antibody in the region of the test line which selectively recognises human IgG. During the test, the anti-SARS-CoV-2 Spike/RBD IgG antibodies react with the nanoparticles present in the test buffer. Subsequently, the mixture chromatographically migrates by capillarity to the top of the test strip membrane, interacting with the Test line region resulting in the appearance of a coloured line, if the sample contains anti-SARS-CoV-2 Spike/RBD IgG antibodies. If these antibodies are not present in the specimen, no coloured line will appear in the Test line region, indicating a negative result. As a procedural control, a coloured line will always appear in the Control (C) line region, indicating that the test has been properly performed and that all the components have worked as intended.

TECH SPECS COVID-19 Neutralising Ab Rapid Test

COVID-19 Neutralising Ab Rapid Test is addressed to healthcare professionals with the aim to check the immune response of those who have been vaccinated or those who have previously contracted the disease:
- high Sensitivity and Specificity standards, when compared to an ELISA test
- safe and accurate results in only 10 minutes
- easy to use and to read.

Why searching for neutralising antibodies?

Spike protein

One of the most important proteins involved in the virus infection process is the Spike protein, which covers the whole virus' surface. This is divided in two portions: the first one contains a region known as RBD (Receptor Binding Domain), that allows the virus to bind to the host cell by adhering to the ACE2 receptor; while the second one allows the virus to enter the cell in a following phase.

This evidence allows to assume that an antibody capable of inhibiting the interaction between the Spike protein and the ACE2 receptor would potentially prevent coronavirus infection and the associated disease. For this reason, among the different classes of antibodies produced, the G-type (IgG) anti-SARS-CoV-2 Spike/RBD are called "neutralising antibodies". Consequently, the Spike protein (or portions of it) has been used as an immunological target in the development of vaccines against SARS-CoV-2.

Similarly, since serological tests are able to detect the body's immune response to a virus infection, those detecting IgG anti-SARS-CoV-2 Spike/RBD IgG can show whether antibodies involved in the process of neutralising the virus responsible for COVID-19 disease have been produced.

Post-vaccination Study

Different studies have been carried out in order to evaluate the use of COVID-19 Neutralising ab Rapid Test in the post-vaccine seroconversion. Data indicated in the table below have been obtained starting from 14 days after the end of the vaccination cycle of Pfizer BioNTech, Moderna and AstraZeneca vaccines.

Vaccine Type Amount of sample tested Seroconversion Rate When should I use the test? Location
Pfizer BioNTech Cominarty 234 98.3%
(95% C.I.: 95.6-99.3%)
Starting from 14 days after the end of the vaccination cycle Cancer National Institute, Oncology Department and Haematology Department (Milan Italy); Interuniversity Center for Research on Influenza and other Transmissible infections (CIRI-IT, Genova, Italy); Istituto Mario Negri (Bergamo, Italy)
Oxford-AstraZeneca 68 98.5%
(95% CI: 92.1-99.7%)
Starting from 14 days after the end of the vaccination cycle PRIMA Lab SA in collaboration with the Biological Laboratory of the Italian Fire Brigade (Laboratorio Biologico dei Vigili del Fuoco, Milan, Italy)
Moderna mRNA-1273 21 95.2%
(95% CI: 77.3-99.2%)
Starting from 14 days after the end of the vaccination cycle PRIMA Lab SA (Balerna, Switzerland)

Post-vaccine seroconversion evaluations are also ongoing on other vaccines, please refer to Table 1, above, for an update of the results.

How does the Test work?

A) Collect the blood sample:
1. Whole blood (fingerstick and venous sampling): fill the blood collecting pipette and transfer 20μL of whole blood sample into the sample well of the test cassette. Alternatively, it is possible to collect the sample using a laboratory micropipette.
2. Serum and plasma: Transfer 10μL of sample to the sample well with a laboratory micropipette.

B) Apply two drops of diluent to the sample well, approximately 80μL.Wait 10 minutes and then read the results. The results are valid for up to 15 minutes after adding the diluent.

Results interpretation

Positive Result: Two coloured lines appear, one in the Control Line region (C) and another line in the Test line region (T). This result means that the test has identified the presence of IgG against SARS-CoV-2 Spike protein. The colour intensity of the control and test lines may vary depending on the concentration of antibodies against SARS-CoV-2 Spike protein present in the sample. Therefore, any colour shade in the T region must be considered as positive.

Negative Result: No line appears in the Test line region (T). The test did not detect the presence of IgG against SARS-CoV-2 Spike protein in the sample. IgG is either not present or is present in very low concentrations not detectable by this diagnostic device.

COVID-19 Neutralising Ab Rapid Test is not conclusive for the diagnosis of ongoing infection, as the absence of antibodies does not exclude the possibility of an early-stage infection.


1. European Centre for Disease Prevention and Control, Disease background of COVID-19 (


3. HUANG, Yuan, et al. Structural and functional properties of SARS-CoV-2 spike protein: potential antivirus drug development for COVID-19. Acta Pharmacologica Sinica, 2020, 41.9: 1141-1149

4. SHANG, Jian, et al. Structural basis of receptor recognition by SARS-CoV-2. Nature, 2020, 581.7807: 221-224