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Antibody Covid Rapid Tests: Accuracy of Tests is all over map

Learn about the role that Covid-19 testing plays in tackling the pandemic. Get information on the various factors that affect the accuracy of 15 min Rapid antibody tests 

Being a new virus, Covid-19 has posed a significant challenge to scientists and researchers. They are working day and night, trying to uncover the nature of the virus. So far, the most significant progress that has been made is testing of individuals to determine the prevalence of the infection in different populations. This is meant to but doctors, scientists, and researchers time to find a permanent solution to the pandemic.

Data resulting from the test is meant to help in tackling the virus in a number of ways. For one, it will tell how far we are from achieving herd immunity. Scientists say that it will take a population to have 70% infections in order to achieve herd immunity. In this case, it will be immunity as a result of previous exposure to the virus. The tests are also there to confirm the presence of antibodies in patients, and whether or not the antibodies can prevent reinfection

Results on active and recovered infections will also go a long way in helping concerned agencies determine if the strategies in place for the containment of the virus are effective. Covid-19 testing holds the key to finding a solution for the pandemic.

Due to the increase in demand by scientists and researchers for the tests, the FDA has allowed several companies to introduce their test kits into the market. The approval, however, comes with several concerns. Some of the rapid test kits are unreliable as they have been seen to produce false negatives and false positives. This has been the main issue in collecting test results and establishing the actual prevalence of the virus.

The companies concerned are making necessary adjustments and doing everything they can to improve the accuracy of their kits. Impressively, some companies have kits with 100% accuracy, with the least going down to 80%: this is excellent news. It is also worth noting that the accuracy of the test kits does vary. 

Factors affecting the accuracy of antibody tests

1. The time when the tests were conducted

The date of the test is one of the variables that affect the accuracy of the antibody tests. Most of the test kits become sensitive at a later time. If the test is done about seven days after the onset of the illness, it might show a false negative. However, as time goes by, the concentration of the virus increases to a detectable level. 

2. What the tests are being used for

It is important to note that the tests are used for different things. While others may be looking for the presence of antibodies after recoveries, some tests are aimed at measuring the prevalence of the disease. Seroprevalence tests are done to identify the percentage of prevalence in a community.

The required accuracy for this test is 90% sensitivity and 98% specificity. The sensitivity of the test kits means that the tests should generate a few false negatives. On the other hand, specificity means that few false positives should be generated. 

3. How a user interprets the results

There have been disparities regarding what is positive and what is not. Unfortunately, most tests do not give a clear direction on what a positive result is, and what is not. This has brought confusion in the recent past. It is up to the companies deploying the test kits to give strict instructions regarding the interpretation of the results. If everyone is on the same page regarding positive and negative results, this variable of accuracy can be tackled. Companies need to start paying attention to clear guidance on how to interpret the results. 

4. Features of the test

The difference in the antibody test kits’ features is a reason for the variance in the accuracy of test results. The main feature to look at in this case is the kind of antibody that the kit is designed to test. Are there different antibodies? As a matter of fact, there are two main types of antibodies used in these tests. They are the IgM and IgG antibodies. The two antibodies are different, and so are the test results for the two types. 

Note that IgM always responds first after an individual is infected. This antibody takes about one week to manifest. Note that with time, the IgM antibody may fade after some time, and undetectable by the kits. Also, the signals of IgM antibodies may be less dominant than the IgG antibodies; they, therefore, may go undetected. 

The detection of IgG, on the other hand, might be less variable than the IgM antibodies. The kits are also able to detect better when the antibodies are combined as with the Covid-Rapid kits. 

5. Viral protein used

The viral protein used to bind the antibodies is yet another variable that will affect the accuracy of antibody tests. The most commonly used viral proteins are the spike protein and the nucleocapsid protein. The latter forms a shell around the viral RNA, whereas the spike protein binds to host cells after studding to the surface of the virus. 

Tests that use the nucleocapsid protein are less specific for one reason: it is conserved across most viruses. On the other hand, the spike protein is less conserved, making it the most preferred reagent for Covid-19 tests. 

The other factors that affect the accuracy of antibody tests for Covid-19 include the way a viral protein is produced. All these factors need to be put in mind when conducting tests for the virus. This will help determine the most appropriate time to test a given antibody, knowing how long it takes to manifest. More so, information on the suitability of a given test depending on the use of the results will help in picking an option that will offer accurate results. With all the mentioned variables affecting the accuracy of Covid-19 tests, there is a need for independent evaluations to be done in order to determine the usefulness of the different tests. This will also help in answering questions such as whether or not antibodies can bring about immunity.

Features of API Covid rapid test kits that make them superior

API COVID-RAPID Covid-19 kits are not the standard rapid test kits. They fill the gap the other test kits have not been able to fill. Here is what makes them unique.

As of May, 23 2020, our API kits show an aggregate of 93.44% Sensitivity & 98.04% Specificity on a sample size of 1,794. Switzerland, Belgium and Harvard showed 100% Specificity and accuracy on approximately 500 patients. 

Most of the test kits in the market have not been able to show accurate results, limiting the determination of the prevalence of the virus in a population. API kits have been shown to possess  100% specificity in the presence of Covid-19 antibodies. The best part is that the API kits capture even asymptomatic cases. That is 6 out of 10 of the cases. 

The kit is also able to capture current and past infections. Note that this is something that different agencies that are tackling Covid-19 are struggling with. This feature can be used as proof of immunity and play a big part in taking Covid-19 management to the next level. 

Paul Singh, MHA, BA

​Covid Antibody Diagnostics​™

A Natures Body Wellness Corporation, Lake Mary FL 32746 

Find us on Google under Antibody Diagnostics

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