WHAT IS A RAPID COVID-19 ANTIBODY TEST?

For the purpose of clarity and this report, The World Nano Foundation (WNF) has identified the Rapid COVID-19 IgM/IgG Antibody Assay Kit by Colloidal Gold Method, with separate readings for IgM and IgG, as the example of a 2nd generation Rapid COVID-19 antibody test.

WNF have chosen this differentiator to highlight the important advantages of using nanoparticles as part of the testing technology. The 2nd generation development of the COVID-19 Rapid Antibody IgM/IgG test has seen the introduction of gold nanoparticles into the testing strip.

This Colloidal Gold Method has been introduced in other applications in the disease testing industry to improve testing accuracy.

The Chinese in their fight against COVID-19 have moved to using these improved 2nd generation testing methods.

The 2nd generation test advantages are:  

• Detects COVID-19 with more accuracy and more information.

• They allow you to perform tests sooner after suspected infection.

• Helps key industries and workers by providing more reliable back-to-work dates.

• Gives healthcare professionals more confidence in triaging patients, to provide the most appropriate treatment paths. 

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To make the right public health decisions, governments worldwide are currently using estimates of transmission rates, case numbers and case fatality rates (CFR). However, given that anywhere from 20-80% of COVID-19 cases are estimated to be asymptomatic, these figures have been very difficult to accurately model. On a population level, this means that the true size and scope of the pandemic is still undefined, leaving policy makers with little indication of how serious of a threat COVID-19 still is, and how long it can be expected to last.

By conducting widespread antibody sampling of the general public, public health bodies could better estimate the true levels of exposure and resulting population immunity. For COVID-19, this would be a game-changer, as true transmission and CFRs could be calculated to forecast the intensity and longevity of the pandemic to direct decision-making. Furthermore, by identifying potential geographical ‘hot-spots’ of low population immunity, health systems could better allocate resources to prevent or manage transmission.

As we are still learning about the virus, it is important that we capture the test data, so policy decisions can be made using safe assumptions on continuing to work in key jobs and safe return to work for those who can be considered immune and non-contagious.

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Rapid COVID-19 Antibody testing helps medical practitioners to decide whether someone tests positive for COVID-19 within 3 minutes, and issues negative readings within 15 minutes.

There are several advantages to the antibody test. Compared to Polymerase Chain Reaction (PCR) test it saves time and it does not require equipment. It is simple to perform and only requires minimal training. It can be performed at the bedside, in any clinic, laboratory, care home, community or business environment. It is more convenient to use fingertip or heel blood, instead of vein blood in these environments. Initial test results using fingertip blood were shown to be as good as that of vein blood, which suggests these antibody test kits can be used for rapid field detection.

Another potential application of this test is identifying asymptomatic carriers, as asymptomatic carriers can freely spread COVID-19 without any warning signs. The antibody test kit makes large scale identification of asymptomatic carriers possible. At least some, if not all the carriers, are likely to have anti-COVID-19 antibodies, as demonstrated by asymptomatic Zika virus carriers.

Because the antibody test can detect IgM and IgG simultaneously, it can also be used in early diagnosis and for monitoring during treatment. Infection has been shown to start in the lungs, not in the upper respiratory tract, therefore, sampling during the early infection stage using throat swabs may not detect the virus. This is one explanation for the number of false negatives in PCR tests. However, this sampling effect would not have any effect on IgG and IgM detection through the rapid antibody test.

The antibody test cannot confirm virus presence, only provide evidence of recent infection, but it does provide important immunological evidence for physicians and doctors to make the correct diagnosis, alongside other tests and to start treatment of patients faster.

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If the Rapid COVID-19 antibody tests prove reliable enough, they can be used to screen large numbers of people, relieving current capacity constraints on the PCR machines, so the accuracy of PCR testing can be used for more precise analysis. Repeat antibody testing would make the screening of large numbers more reliable and more informative.

The combined capability of Rapid COVID-19 tests with the PCR tests would enable public health policy to be more effective in slowing the spread of the virus and getting people safely to work.

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Moreover, the correct testing strategy can give an indication of which stage of the virus a worker is in, giving more accurate timelines for back-to-work dates, and allowing governments, trade bodies and businesses to declare non-contagious and immune workers fit to safely return to work.

It is vital that all key workers are regularly tested, regardless of if they show symptoms or not, as positive asymptomatic workers could be unknowingly, actively spreading COVID-19 to others in the workplace.

According to thinktank, the Resolution Foundation, the UK government’s plan to subsidise the wages of workers affected by the Covid-19 lockdown of the economy could end up costing the Treasury £40bn for every three months the scheme is operating. Therefore, by getting people safely back to work, via mass testing, policy makers are aslo lessening the huge financial strain this crisis will have on economies across the world.

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How accurate, is accurate enough?

Firstly, you need to know how many times the test produces the right diagnosis. Then, you need to know how many times the test gets the diagnosis wrong. The wrong diagnosis is when you either test negative for the virus when you do have it (called a false-negative), or you test positive for the virus when you don’t have it (called a false-positive).

The government models how many false-negatives and false-positives can be tolerated for the virus to be defeated. How easily the virus spreads, and government policy on social distancing, isolation, hygiene and any other criteria that are important to that government, will be the key factors that make up the model. With disciplined recording of test results, the models can continue to be validated and adjusted as necessary.

Accuracy levels can be boosted through diagnostic protocols and repeat testing. For example, in repeat testing, if a 90% accurate test is repeated, then mathematically the test accuracy of using the same test method a second time goes up to 99%.  A similar approach was used during the Ebola crisis, where rapid tests were repeated within 15 minutes to create more validation and accuracy.  This novel approach proved very successful.  It would also significantly improve the speed of testing, and importantly not decrease accuracy.

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Providing the testing methods that you are using are 90%+ accurate, then these are the implications of false test results.

Definitions

A false positive is when the test result indicates a person has COVID-19 when in fact they don’t. They do not have the virus.

A false negative is when the test result indicates a person does not have COVID-19 when in fact they do. They have the virus.

Implications

False positive results simply remove people from their workplace and society to self-isolate in order to prevent the virus spreading. This has little negative impact, other than on key workers unnecessarily isolating when they don’t need to for a short time.

False negatives are always undesirable because the person being tested is contagious and doesn’t think they are. However, their behaviour shouldn’t change because everyone should behave as if they have the virus to stop the spread until it is defeated.

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As the crisis continues to evolve, and pressure mounts on world governments to provide practical testing solutions for the masses, the number of different testing solutions also increases each day. So, how can policy makers devise workable testing strategies in this overly complex, highly pressured and ever-evolving environment?

Transparency is the answer. Currently, several manufacturers following best practices are trying to be incredibly open and transparent regarding the test data and functionality of their solutions, and it is important more follow suit. Government testing bodies also need to be transparent about the requirements they expect tests to fulfil, and provide testing data so that test solution providers know how their tests performed under scrutiny, instead of just announcing whether different tests do or do not work.

The variation of tests with varying degrees of accuracy, speed and ease of deployment create a spectrum, from which policy makers can work out the best function for different tests.

How accurate is accurate enough?

To work out the answer to this question, we must first ask; what functions do we want tests to perform? It is also important to recognise that no test is 100% accurate and all tests must form part of a diagnostic protocol.

If you have a large group/community of people, whose infectious status (Positive, Negative, Immune) is unknown, then testing solutions with different accuracy levels can provide different functions.

For example, if you have a test that is 90% accurate, which can be done as a rapid point-of-care test, you can quickly establish with 90% accuracy the size of the problem in a previously unmeasured group. This provides vital data to policy makers for how to manage that group accordingly.

To increase the functionality of that test, policy makers may decide to test a person multiple times, so again using the example above, statistically the accuracy goes up to 99% with the second test and beyond with each subsequent test. They could also test people with the same type of test but made by a different manufacturer, this would enable results to be cross-referenced, and use tests in the most efficient manner by understanding the inherent strengths and weaknesses of different tests.

With mass testing of this nature in progress, policy makers can learn from the results and understand the function of each test used and develop testing programs that are tailored to specific sub-groups of people. For example, you may use one test to triage a group of people, another test to provide confirmatory results, and a final testing solution, such as PCR testing, for more precise analysis of a smaller number of the sub-group.

By having mass testing programs in place, policy makers can quickly change the tests being used as more effective, or more accurate tests become available. The creation of the mass testing process may be more important than what tests you start the process with.

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Technology is being currently perfected, which would use quantum dot technology to track people’s test results and provide an easy to manage and comprehensive testing and health status, presented on a smartphone as an authenticated and validated identity record along with a colour- coded “traffic light” indicator.

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It is likely that nanotechnology innovations will also be used to fight the virus, for example Thomas Webster, who specialises in developing nano-scale medicine and technology to treat diseases at Northwestern University, has proposed using nanoparticles to disrupt the virus in the body.

Nanoparticles of a similar size could be used to attach to SARS-CoV-2 viruses, be disrupting their structure with a combination of infrared light treatment. That structural change would then halt the ability of the virus to survive and reproduce in the body.

Nanotechnologists are also working on a more generic vaccine that will be effective against families of viruses instead of specific viruses. This would give excellent global protection particularly for vulnerable people.

Meanwhile, nanotechnology is also offering therapeutic solutions, such as the nebuliser being developed by Dr Su Metcalfe and LIFNano. The device, which is similar to an asthma "puffer", is loaded with LIF nanoparticles for supply directly into the airways and lung tissues. This technology uses natural protection to help people recover their lung function quicker, and protect patient’s lungs against future infections. It also distinguishes between killing the virus and crucially, not killing the cells of the patient, especially the delicate tissue of the lungs.

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