Scientists have estimated that around one-third of the people who are currently suffering from COVID-19 do not any of the registered symptoms of COVID-19, and so could be spreading the virus unknowingly. In order to help tackle this, the UK government rolled out rapid lateral flow antigen tests (LFD) aimed at detecting cases of Coronavirus in under 30 minutes – so that people who tested positive for coronavirus could immediately isolate themselves.
However, the lateral flow test accuracy has been called into question more than once, and the value of this sort of mass testing is currently under debate. We take a closer look at the reliability of COVID1-19 lateral flow tests and what employers need to know about them.
What are lateral flow tests?
Lateral flow tests are tests that are able to process COVID-19 samples quickly and without the need for laboratory equipment. They are different from the polymerase chain reaction (PCR) tests that Test2Go also offer, as these look for genetic material from the virus and so are generally felt to be more sensitive.
The main benefit of lateral flow tests over PCR tests is that they generate results in under an hour, and can be used quickly at home, rather than having to send your swab back to our labs to process the result.
Back in December 2020, the Medicines and Healthcare Products Regulatory Agency (MHRA) issued an Exceptional User Authorisation (EUA) to the Department of Health and Social Care allowing the use of a certain lateral flow self-test to detect the coronavirus infection in asymptomatic individuals who may otherwise not be tested.
The EUA is used when a manufacturer applies to supply a medical device that does not comply with the law to protect a patients health, but there is no legitimate alternative available.
What this means is that the lateral flow test can be used by a member of the public, in their own home or at a place of work, even if they have no previous experience of testing.
How does the lateral flow test work?
The science behind the lateral flow test was established to detect the presence of a particular protein target, and it is widely used as it is affordable, easy to use and delivers fast results. Probably the most well-known lateral flow test in use previous to the coronavirus outbreak was the pregnancy test.
In the case of coronavirus, the lateral flow tests target is the proteins, or antigens, that are found in the COVID-19 virus.
The coronavirus lateral flow test is taken using a hand-held device with an absorbent pad at one end and a results window at the other. Inside the device is a strip of test paper that will change colour if the presence of COVID-19 antigens is detected.
What do the results of a lateral flow test mean?
If you get a positive result from a lateral flow test then it is extremely likely you are currently infected with COVID-19 and so risk infecting others. You will need to report this result on the NHS track and trace system, and then also take a PCR test in order to confirm the result.
If a negative result is received from a PCR Test, then the test was not able to deter the COVID-19 virus in the sample, but the person may still be infectious and so social distancing rules should still be followed.
Are lateral flow tests 100% reliable?
No. The MHRA has actually stated that “no test is 100% reliable” even those tests that meet their regulatory standards for safety and performance.
They emphasise that lateral flow tests are only authorised to be used as a “red light” test to find infectious people and ensure they self-isolate quickly. They should not be used as a “green light” test to allow people who have achieved a negative result to enjoy greater freedoms.
Lateral flow tests are unable to detect very low levels of coronavirus in a sample – which a PCR test is able to do. This means lateral flow tests may not give a positive result to someone who has coronavirus if they have only recently been infected, are in the incubation period, or are at the end of the infection.