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What is SARS-CoV-2?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the name given by the International Committee on Taxonomy of Viruses (ICTV) to the virus responsible for causing the disease, COVID-19.

We have a vaccine now, do we need testing anymore?

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.

How accurate are your tests?

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.

How frequently should employees or visitors be tested?

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.

Why does the KnowNowᵀᴹ test use a saliva sample?

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:

  • The sample collection method requires a swab to be inserted into the patient's throat and/or far into their nostril and rotated, causing discomfort to patients due to the procedure’s invasiveness, and even inducing bleeding in their tonsils and posterior pharynx. (1)
  • The discomfort or even pain of the sample collection method has a detrimental impact on compliance for serial testing, as patients are unwilling to subject themselves to the test on a regular basis. (2)
  • Nasopharyngeal sample collection presents a considerable risk to healthcare workers, because it can induce patients to sneeze or cough, expelling virus particles. (2)
  • There are several situations where nasopharyngeal swabs would cause particular harm, such as in patients with coagulopathy, those undergoing anticoagulant therapy, or those with significant nasal septum deviation. (3)
  • These tests are not always successful at the first attempt, even though performed by trained healthcare workers, and shortages of swabs and protective equipment are frequently reported. (3)
  • They show relatively poor sensitivity for SARS-CoV-2 detection in early infection and are inconsistent during serial testing. (2)

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

Where do you make your KnowNowᵀᴹ tests?

KnowNowᵀᴹ Tests have been invented, developed and manufactured in the UK.

How is a KnowNowᵀᴹ Test administered?

There are just 4 simple steps to the KnowNowᵀᴹ Test.

  1. Swab the mouth: The KnowNowᵀᴹ Test requires just a saliva sample to be taken easily and comfortably from the mouth. We know how uncomfortable and painful other lateral flow antigen tests or polymerase chain reaction (PCR) tests can be, with swabs going high into nostrils and all the way back to tonsils. It was really important to us that people would feel happy to take a KnowNow test on a regular basis.
  2. Shake the tube: The saliva swab is placed into a buffer solution in a small tube, and shaken up to mix it well.
  3. Squeeze on panel: A few drops of the mixed solution is squeezed onto the KnowNowᵀᴹ Test device.
  4. Know in 15 minutes: It takes just 15 minutes for the positive or negative result to appear in the test result window on the KnowNowᵀᴹ Test device. No need to wait 24-48 hours for results, as you would with a PCR test.

How sensitive is the KnowNowᵀᴹ Test?

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.

How long will it take a qualified clinician to administer each test?

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.

What is a KnowNowᵀᴹ Test?

The KnowNowᵀᴹ Test is the UK's only on-the-spot COVID-19 test that uses just your saliva to tell you if you are currently able to infect someone else with COVID-19.

Unlike other tests, the KnowNowᵀᴹ Test won't give you a positive result if you have been exposed to the SARS-CoV-2 virus in the past, but are no longer able to infect other people.

How does KnowNowᵀᴹ compare to other COVID-19 lateral flow antigen tests?

The KnowNowᵀᴹ Test is unique to other lateral flow antigen tests in 3 key areas.

The first key difference is that the KnowNow test needs only a saliva sample, which can be taken easily and comfortably from the mouth. Other lateral flow antigen tests usually need a nasopharyngeal, anterior nasal or tonsil sample, all of which are painful and unpleasant for the individual being tested and more challenging to collect effectively for the clinical professional administering the test. No one wants to be made to cry or gag, or make someone else cry or gag, on a regular basis!

The second is that the KnowNowᵀᴹ Test looks specifically for live virus which would cause the individual tested to be able to infect others. Although other lateral flow antigen tests are often said to test whether an individual is infectious, this is because they have a higher Limit of Detection and can only detect the virus when there are more viral particles present in the sample. As a result, they offer a proxy measure for infectivity, rather than directly testing whether there is live virus in the sample. The KnowNowᵀᴹ Test on the other hand is a true infectiousness test, which uses a unique patented mechanism which detects a completely different part of the virus.

Finally, the KnowNowᵀᴹ Test is also more sensitive than other rapid antigen tests available, as it is able to pick up the presence of the virus even when there is much less of it present in the sample. Our Limit of Detection is between 50,000 and 200,000 viral copies per mL, whilst the Abbott BinaxNow test, for example, needs 1,000,000 viral copies per mL in order to get a positive signal.

Had COVID - 19 symptoms in the last 2 days? Apply here to help us make testing accessible to all.