We chose to design our unique KnowNowᵀᴹ test for COVID-19 infectiousness to work with a simple saliva sample, so that it would be comfortable and easy to administer, and to ensure that anyone would be happy to take a test every day if required. We believe that patient comfort and happiness leads to increased participation in routine testing, and ultimately increases the probability that COVID positive patients can be detected before they've had a chance to infect others.
The focus of our first clinical study was to assess the feasibility of using saliva sampling, to refine our saliva collection method, and also to assess the overall usability of the KnowNow test. This was a UK Government-supported National Institute for Health Research (NIHR) study carried out across ten UK hospitals with 100 patients participating. Through this study we determined that saliva sampling was both effective and user-friendly, and identified a specific swab for sampling. We chose not to opt for a spit collection method for our saliva sample, as providing a spit sample can be challenging for some patients, particularly the elderly or those suffering with COVID-19 symptoms.
For other COVID-19 tests, throat and nasopharyngeal swabbing is one of the most common types of sample collection. However, a number of studies have explored various issues with these types of sample collection, including:
Some tests have been designed to work with anterior nasal swabs, as a somewhat less invasive alternative to nasopharyngeal swabs. However, there is some evidence to suggest that nasal swab testing produces less sensitive results and may miss patients with lower viral loads (4).
References:
(1) Exploring salivary diagnostics in COVID-19: a scoping review and research suggestions
(2) Saliva is more sensitive for SARS-CoV-2 detection in COVID-19 patients than nasopharyngeal swabs
(3) Saliva as a Candidate for COVID-19 Diagnostic Testing: A Meta-Analysis
(4) Nasal-Swab Testing Misses Patients with Low SARS-CoV-2 Viral Loads
If there is one red line visible next to the "C" in the KnowNowᵀᴹ device test results window, and any line at all, no matter how faint, appears next to the "T", then the test result is positive. This indicates that the SARS-CoV-2 antigen has been detected in the sample.
Following a positive result, current government guidance on matters including self-isolation and reporting the result should be followed.
A lateral flow test is a simple diagnostic device designed to detect the presence or absence of a target substance in a liquid sample without the need for specialised and costly equipment.
The most commonly recognised type of lateral flow rapid test strip is the pregnancy test.
If you have already activated your sample pack please go to the activation link that we emailed to you. Alternatively, if you fill in your email again we will re-send the activation link to you.
The KnowNowᵀᴹ Test has been invented, developed and manufactured in the UK by Senseutics Limited, trading as Vatic.
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.
No, there's no limit at all. KnowNow is specifically designed for frequent testing in order to offer the best chance of identifying infectious individuals as early as possible.
We recommend that individuals are tested as regularly as possible to keep workplaces and communities safe. Depending on the scenario, we would recommend that testing is performed every 2-3 days, or even daily, depending on the scenario.
Receiving a negative result means that the individual tested does not have any live virus in the sample provided and is not currently infectious to others. However, it's important to be aware that they could still be exposed to the SARS-CoV-2 virus following the test. It could also be possible that the individual tested has already been exposed to the virus 1 or 2 days ago, and they have not yet become infectious to others.
As a result, we recommend that individuals are tested as regularly as possible to keep workplaces and communities safe. Depending on the scenario, we would recommend testing is repeated every 1 to 3 days.
From our own studies with partners, we estimate that a clinical professional can administer one test every 3.5 to 4 minutes. This assumes that they collect saliva samples from individuals, set the KnowNowᵀᴹ Test devices aside to develop for 15 minutes, and collect samples from further individuals before reading the results from earlier tests.
If there is one red line visible next to the "C" in the KnowNow device test results window, and no line at all next to the "T", then the test result is negative. This indicates that no SARS-CoV-2 antigen has been detected in the sample.
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 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 reading 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.