There have been questions raised around the sensitivity of rapid lateral flow antigen testing for SARS-CoV-2 as compared to PCR testing. However, these questions have been strongly challenged by the scientific community.
PCR tests identify the presence of the SARS-CoV-2 virus in the body, regardless of whether the virus is actively infectious. The PCR testing process amplifies the genetic code of the virus so that even minuscule amounts of the virus in the sample can be picked up. This makes for a powerful test, but since viral fragments can linger in the body for weeks even after the infection has cleared, infected individuals being tested using PCR will show as positive for a median period of 22–33 days in total. On the other hand, most people infected with SARS-CoV-2 are contagious only for 4–8 days.
So whilst PCR testing for SARS-CoV-2 may have been considered the "gold standard" test up until now, it will by definition show different results when compared to lateral flow tests which aim to identify individuals based on viral loads which suggest they are within their infectious window. This discrepancy between what each test is actually testing for has caused some issues where PCR testing has been used to evaluate the effectiveness of lateral flow tests, such as in the mass testing rolled out in Liverpool in November 2020.
The KnowNowᵀᴹ Test goes a step beyond other lateral flow tests with its unique, patented detection mechanism which only shows a positive result when live infectious virus is identified in the sample. As a result, PCR tests will similarly show different results to the KnowNowᵀᴹ Test in certain cases, since they will show positive results even for individuals outside of their infectious period.
For a much more comprehensive and referenced answer, you may like to read "Clarifying the evidence on SARS-CoV-2 antigen rapid tests in public health responses to COVID-19" from the Lancet.
The KnowNowᵀᴹ test will provide a result within 17-18 minutes of an individual arriving for their test.
The process of taking the saliva sample, mixing it with the buffer solution and dropping it onto the KnowNow test device should take a clinical professional no more than 2 to 3 minutes.
It then takes just 15 minutes for the test result to develop in the KnowNow device test results window.
The test result should not be read and interpreted after 60 minutes. If it wasn't possible to read and interpret the results between 15 and 60 minutes after dropping the solution into the sample well, the test should be discarded and the process repeated with another new test and saliva sample.
We're so pleased that you'd like to order our KnowNowᵀᴹ Tests. At the moment we are running some pilots with a few key partners, before distributing our tests more widely.
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Vatic was founded in October 2019 by Alex Sheppard and Dr. Mona Kab Omir.
When the first wave of COVID-19 started in the UK in early 2020, our team immediately saw an opportunity to contribute to global efforts to tackle the pandemic, and leveraged work already underway on antigen testing to quickly start developing the KnowNowᵀᴹ Test.
It should not be necessary to perform more than one test on a given individual at a single point in time, unless the KnowNowᵀᴹ device test results window displays no lines at all, meaning that the test has failed, or unless it was not possible to read the test results within 15 to 60 minutes of applying the mixed saliva and buffer solution to the KnowNowᵀᴹ device.
However, receiving a negative result does not mean that the individual tested can't be exposed to the SARS-CoV-2 virus following the test. So we do recommend that individuals are tested regularly to keep workplaces and communities safe. Depending on the scenario, we would recommend testing is repeated every 1 to 3 days.
The KnowNowᵀᴹ Test's specificity is 99.9%. In more than 300 negative patient saliva samples, it hasn’t returned a single false positive result.
This is so important for getting life back to normal. We don't want anyone to be stopped from going to work, heading off on holiday or socialising at events, when actually it would be perfectly safe for them to do these things.
Specificity is particularly important when disease prevalence is low and tests are intended to be used at enormous scale. For example, if a test with just a 3% false positive rate is used on one million people per day, that would result in 30,000 people per day being falsely identified as infectious with COVID-19 and being unnecessarily asked to self-isolate.
We recommend that tests are performed at the earliest opportunity possible, to ensure that individuals in the workplace, venue or community don't come into contact with each other prior to testing.
There's no particular time of day that's best to perform a test. Although it is important that individuals haven't had anything to eat or drink, and haven't smoked, within the 30 minutes prior to taking the test.
We’re focused on developing our predictive health technology and tests so that we can make medicine more proactive and help to predict illness before it becomes acute or infectious. We want to empower people to feel in charge of their own health and wellbeing by making testing more readily accessible and available, allowing for earlier prediction and prevention of acute illnesses.
COVID-19 test accuracy is typically determined by ‘specificity’ and ‘sensitivity’.
Specificity is about the extent to which you can eliminate false positives; sensitivity is how much virus needs to be present before a test picks it up. So there is always a need to strike a balance, when testing, between trying to pick up the virus as early as possible, versus accidentally delivering a positive test result for someone who is not actually infected.
The specificity of the KnowNowᵀᴹ Test is 99.9%. In more than 300 negative patient saliva samples, we haven’t had a single false positive.
What’s important when it comes to sensitivity is how much virus needs to be present in the patient sample for the test to give a positive signal. This is known as the 'Limit of Detection', and we measure this rather than clinical sensitivity as it is much more informative. Our Limit of Detection is between 50,000 and 200,000 viral copies per mL, making our test more sensitive than other rapid antigen tests available. The Abbott BinaxNow test, for example, needs 1,000,000 viral copies per mL in order to get a positive signal. The KnowNowᵀᴹ Test's very low Limit of Detection means it can detect infected people as early as day 3 to 4 of infection. This is before they become highly infectious, and a day or two earlier than most tests available (based on models of viral load in disease progression).
If you'd like to read more about this subject, we recommend this paper. It argues that the "Limit of Detection matters and directly impacts efforts to identify, control, and contain outbreaks during this pandemic" since "higher LoD are likely to miss nonnegligible fractions of infected individuals." It also makes the case that Limit of Detection values for tests using universal standard metrics should be readily available in the public domain to enable like-for-like comparison.
We recommend that individuals are tested as regularly as possible to keep workplaces, venues and communities safe.
It is important to remember that individuals can still go on to be exposed to the virus following a negative test result. Additionally, a high proportion of infectious people show no symptoms at all, and so regular testing is key to breaking the chain of transmission.
Depending on the scenario, we would recommend that testing is performed every 2-3 days, or daily, depending on the scenario.
Although vaccine rollout is progressing extremely quickly in the UK, the government expects that it will be the end of July 2021 before every adult in the UK has been offered their first dose of a COVID-19 vaccine. Second doses should be received around 12 weeks after the first, and so it is likely to be the end of October 2021 before every adult has received both doses.
In the meantime, whilst we await full vaccine rollout, regular rapid antigen testing offers a way to enable the re-opening of society.
Beyond this, it is also important to consider that no vaccine is 100% effective even after 2 doses, that not everyone will accept or be able to have the vaccine, and that there is uncertainty as to whether the vaccines will work effectively against current or future mutations of the virus. We should also consider the fact that the UK is very much ahead of other countries around the world in progressing its vaccine rollout, and that it will still be some time before the vast majority of people globally will be vaccinated.
With these factors in mind, regular testing is likely to play a role in keeping societies safe and open for some time to come.