COVID-19 testing stories, Ads and articles are commonplace. With antigen lateral flow tests and PCR tests probably being most familiar. But are they the only testing solution for supporting a pathway out of the COVID-19 pandemic? They certainly play a role. However, there is another solution that has the potential to be more powerful: neutralising antibody rapid tests.

Therefore, this article will answer 2 questions about the technology: What are COVID-19 neutralising antibody rapid tests and why use them?

You will notice we used the term ‘neutralising antibody test’ rather than just ‘antibody test’. There is an important reason for this which will be explained.

What are neutralising antibodies?

Before moving on it is important to know what neutralising antibodies are.

antibodies and virus molecules

Following infection, the body produces antibodies that target two specific parts of the SARS-CoV-2 (COVID-19) virus: the Nucleocapsid protein and the Spike protein. The coronavirus nucleocapsid protein is a multi-functional protein1 and the spike protein is integral in penetrating human cells and initiating infection.

Neutralising antibodies bind to the SARS-CoV-2 Spike protein and interfere with the virus’ ability to enter human cells. IgG antibodies are the most common antibody in blood and have the largest part to play in conferring immunity to bacteria or viruses.

Immunologically, antibodies to the Nucleocapsid protein are necessary but in the context of pandemic, IgG neutralising antibodies to Spike protein hold the key.

What are COVID-19 neutralising antibody rapid tests?

A neutralising antibody rapid test, such AbC-19TM Rapid Test, is a lateral flow test that detects IgG antibodies from a small finger prick of blood in only 20 minutes. AbC-19TM is a point of care test for use in multiple testing locations and has high sensitivity and specificity. Meaning they have the potential to play a vital supporting role out of the pandemic.

Currently, antibody tests detect antibodies targeting two different proteins on the SARS-CoV-2 virus:

  • the Nucleocapsid protein
  • the Spike protein

A positive result using each test can confirm prior infection with SARS-CoV-2. However, a positive result with a neutralising antibody rapid test detecting antibodies to the SARS-CoV-2 spike protein holds more significance. This is owing to their infection neutralising capabilities2.

In contrast, a positive test detecting antibodies to the Nucleocapsid protein does not prove whether the body has developed the capability to defeat the infection.

Why use neutralising antibody tests?

There are 3 main uses for neutralising antibody tests:

  • Monitor or detect prior COVID-19 infection
  • Confirm if someone has produced an immune response following infection
  • Monitor antibody vaccine response

a man presenting a conference after COVID-19 restrictionsAntibody testing until recently was solely focused on monitoring COVID-19 throughout populations. As more is known about COVID-19 and as governments fight to save economies, antibody testing is increasingly more important. But, as mentioned earlier, testing needs to be focused on neutralising antibodies.

Antigen testing holds an important role but if you get a negative antigen test result, what next? Have you had the virus? Do you have IgG neutralising antibodies to SAR-CoV-2?

This is where the ability to test an immune response becomes vital, especially in multiple testing locations. Something the aviation and transport industries could possibly agree with.

On this subject, new-medical.net succinctly paraphrased research from Queen’s University Belfast by saying:

Largescale antibody testing would help to identify immune individuals, allowing them to enjoy the benefits of social activity. But, critical for contagion, negative antibody testing would identify those that are not immune, compelling…individuals to be more cautious…’

Vaccine research is mainly focused on the Spike protein as the target. These vaccines are designed to “train” the immune system to recognise the Spike protein. Meaning the body produces antibodies to neutralize the effect of SAR-CoV-2.

Using companion neutralising antibody tests with SARS-CoV-2 vaccines has the potential to help further understand the longevity of immunity. Opening the discussion on the value of pre-screening patients prior to vaccination, which could help support immunisation usage and deployment. In addition, monitoring antibody response in the months and years following vaccination – or indeed following infection – provides data to help guide a pathway out of lockdowns.

Performance data for the use of rapid neutralising antibody tests with the Pfizer-BioNTech vaccine can be found here.

Driving a return to normal life

Greece identified the need for antibody testing and announced it was prepared to allow Britons into the country if they can prove they have COVID-19 antibodies. But considering 34 million international flights arrived in Greece in 2019 (Source: Statista.com), COVID-19 antibody testing programmes need to employ rapid diagnostic methods.

busy airport after COVID-19 restrictions are liftedSome reading this will say, “just use laboratory testing in advance of arriving at the airport”. This can play a role. However, you cannot time when COVID-19 infection happens or when asymptomatic individuals produce antibodies etc. Testing must take place as close to the point of need as possible. Maybe testing must become routine before airport check-ins?

COVID-19 vaccines are being deployed in the millions and there is a sense in some countries of nearing the end of social restrictions. But, of course, evidence gathering, and appropriate management tools and strategies are needed to avoid complacency.

Understanding immunity and response to vaccination must be part of any ‘COVID-19 pandemic exit strategy’. And Abingdon Health strongly believes rapid neutralising antibody testing needs to be front and centre.

To further answer ‘what are COVID-19 neutralising antibody rapid tests and why use them?’, Abingdon Health has produced a White Paper. It explains the use AbC-19TM Rapid Test as a companion test to SARS-CoV-2 vaccination. Alternatively, visit the AbC-19TM product page.

References

  1. McBride, R et al.The Coronavirus Nucleocapsid Is a Multifunctional Protein. Viruses. 2014 Aug; 6(8): 2991–3018. doi: 10.3390/v6082991.
  2. McAndrews, KM et al. Heterogeneous antibodies against SARS-CoV-2 spike receptor binding domain and nucleocapsid with implications for COVID-19 immunity. JCI Insight. 2020 Sep 17;5(18):e142386.
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