How Accurate Are Lateral Flow Tests?
Covid-19 testing has become a key part of our daily lives, with many choosing to continue taking the tests post-pandemic to ensure they are not carrying the virus and to abide by the necessary travel restrictions placed on certain countries.
Studies suggest that over 1.5 million people in the United Kingdom have tested for Covid-19 in the last 7 days, suggesting that to many it is still a key part of their lives. Whether it is for work-related reasons or personal ones, continuing to test can be a great way to prevent the spread of the disease any further for another pandemic.
However, many choose not to continue testing due to concerns regarding the accuracy of lateral flow tests. With many asking exactly, “how accurate are lateral flow tests?”, it seems that confidence has been lost in the once-crucial pandemic tool.
Research has found that lateral flow devices miss between 20% and 81% of positive cases in the different settings - 20% at the Test and Trace centre, 29% in the city-wide mass testing, and 81% in the university screen testing.
In this article, we will take a look at how accurate lateral flow tests are and what influences can change their accuracy. Keep reading to find out everything you need to know about lateral flow tests, how they work, what they’re for and how accurate they actually are.
What Are Lateral Flow Tests?Lateral flow tests are medical testing kits designed to detect the presence of viruses and antigens inside of the human body. In more recent years they have become inseparable bonded to Covid-19, with many believing that the tests can only be used for the virus. However, lateral flow tests have existed long before Covid-19, and different industry sectors and different countries use varying terminology to describe what lateral flow tests are.
Going by names such as Dipstick, Quick Test, Rapid Test and Test Strip, the lateral flow test is recognised worldwide as an accurate and reliable source of medical information if done correctly. During the peak of Covid-19 lateral flow tests were used as the first line of defence against the ongoing virus, being rolled out internationally to households and businesses alike to identify hotspots of infection and limit their contact with the outside world.
We found that the Covid-19 lateral flow test was first developed in Russia by the State Research Centre of Virology and Biotechnology VECTOR, and had the earliest traits of the more modern rapid antigen tests and lateral flow testing kits. Production for these tests began on the 24th January, with the protocol for how to produce and manufacture them becoming available for other nations on the 28th January. The testing kits were approved at a faster speed than most as a result of the urgency and mounting threat that Covid-19 posed to the world - by speeding up the approval process, more testing kits could be made internationally to help limit the spread as fast as possible.
Following on from the Russians, on the 15th August 2020, the US FDA granted an emergency use authorisation for a saliva test developed at Yale University that provided Covid-19 results within hours of usage. Unbeknownst at the time, the US scientists at Yale University had created the first stage of PCR testing - with lab drawn results - that would ultimately have a greater impact on Covid-19 resistance in the future. However, at the time, it helped to inspire innovation and development of the current lateral flow test structures to provide us with the testing kits that we use today.
Our research has found that simply stated, there is no difference between a rapid antigen test and a lateral flow test. This is because the rapid antigen tests use the lateral flow technology to become effective, meaning that in a sense they are both made to work the same way. Using this information, it could be argued that lateral flow tests are either a variant, or a subsection, of the standard and more well-known rapid antigen tests that came to use during the peak of the pandemic and post-lockdown.
How Do Lateral Flow Tests Work?Although lateral flow tests have taken up residence in houses around the world for a number of years now, there is still much ambiguity about how exactly they work. The vast population rely on the brief instruction manual included with each pack for instructions on how to operate the tests - however, these instructions fail to mention how the test works specifically, and how you can maximise your chances of an accurate testing result.
Lateral flow tests are a variation of the ELISA in which antigens are immobilised on a strip of cellulose or other suitable matrix. The sample is then applied at one end of the strip and any antibodies present diffuse along it until they reach the position where the appropriate antigen is immobilised. The test works by binding the specific antigens using antibodies that can then be detected by using labelled detection antibodies, or the solution that your sample is added to.
Your results are displaced towards the end of the process, where the sample diffuses along the strip towards an ‘activation window’ the end of the device is pressed down to puncture the film across the reservoirs, releasing their contents to mix with the sample. This is then drawn back across the strip to remove debris and ensure the sample crosses the antigens twice, which also helps to improve test sensitivity and accuracy.
In layman’s terms, similarly to the rapid antigen tests, they work by detecting the proteins found in the Covid-19 virus and determining whether it is in your body from that information. They are able to do this because as your immune system attempts to fend off a virus, it produces antibodies to attempt to counteract them and dispel them from the body. If Covid-19 antibodies are present in the sample, it would indicate that the body has recently had to fight or is fighting off Covid-19. However, this means that those who have taken a Covid-19 vaccination shortly before testing will most likely test positive, as antibodies may have been produced in response.
One of the most integral parts of Covid-19 testing is purity and sterilisation. If a test or workspace is contaminated, you could risk damaging the accuracy of the test and producing a fake result. Typically, the swabs used in the lateral flow test kits will be sterilised using either ethylene oxide or radiation. The method used to sterilise a swab will be displayed on the packaging of the test, and will be marked with either ‘EO’ or ‘R’ to the corresponding method.
To use a lateral flow test, you need to swab a sample from the back of your throat and from your nose, or just from your nose, depending on the type of test you are using. You should make at least 5 complete circles in both your nostrils and your throat to collect as much sample as possible, which can then be dipped into the extraction solution in the pipette. Once the pipette has been filled with the sample, take the swab out, close it, and add 2 drops of the liquid to the lateral flow test’s paper pad.
Once the test has been completed, you should use the provided plastic bags to dispose of any potentially contaminated materials (including the pipette and your swab). This will help to prevent the virus from spreading through direct contact with your sample. You should wait to see results from between 15 and 30 minutes after the sample has been tested, depending on the type and brand of testing kit used. Unlike a PCR test, you do not need to send your sample to a lab, and it can all be completed at home.
Because of the way that they are prepared, lateral flow tests have a high base accuracy. However, like any test, the accuracy falls the second that they leave the controlled areas of a lab and into the highly infectant and contaminating public world. This means that the accuracy of the test can vary depending on a number of factors, including but not limited to location, time, usage, storage and sterilisation methods.
What Are Lateral Flow Tests For?
Lateral flow tests were brought to the spotlight of the medical world as a result of the Covid-19 pandemic. Introduced as new and revolutionary equipment that geared us to fight the rapidly spreading virus, it helped to stop the spread and save lives across the nation. However, it is a little known fact that lateral flow tests have existed for a long time before the Covid-19 pandemic, and that the Covid-19 lateral flow tests is merely a variant of the test. In reality, you can use a lateral flow test for many different reasons, disease-related or not.The most obvious reason for using a lateral flow test is to identify if you have been infected with the Covid-19 virus. For the past few years, people across the world have been using these tests at home to ensure that they and their family are Covid-free and able to continue on with their daily lives. Believed to be a short-term necessity, lateral flow testing has evolved to become a daily part of many people’s lives even now - healthcare workers, airline operators and drivers internationally are often still required to regularly test to ensure they do not become superspreaders of Covid-19.
One of the more modern ways you can use a lateral flow test is for travel; the self-test kits can be used for a range of different things, more recently to confirm you are fit to travel. We found that Covid-19 rapid antigen tests are accepted by the EU and UK, provide results within 15 minutes and are popular in most modern countries. By using these at-home tests, you can confirm flight availability, your eligibility to travel and your personal safety to foreign countries who may not otherwise allow you access.
In the age of conspiracy theories and mysteries, lateral flow testing can be the perfect way for people to maintain international travel without choosing to get the vaccine, whether that be for health reasons or personal ones. Although research suggests that the vaccine is 90% effective against lab-confirmed, symptomatic infection and 100% effective against moderate and severe disease as of Phase 3 trials, the lateral flow test offers an equally reliable and efficient alternative prevention method to getting the virus.
Furthermore, lateral flow tests can be used as proof of availability for work. In many countries, such as Spain, the economy is heavily reliant on tourism and sales in confined places often in public. We found that contact with respiratory droplets from talking, coughing, and sneezing during face-to-face exposure is the most common way that Covid-19 is transmitted, with direct inhalation of infected particles and contact transmission via oral, nasal, and eye mucous equally important methods of spreading the virus. By testing frequently, people can prevent exposure of Covid-19 to others at work through transmission and can safely continue to help the economy rebound and recover once more.
With over 514,605,757 total Covid-19 positive tests, and 1,546,244 in the last 7 days alone in the UK, it’s no surprise that people are continuing to test for various different reasons but for the same conclusion - to make sure they don’t have Covid-19.
How Accurate Are Lateral Flow Tests?
As we found earlier, the accuracy of lateral flow tests can vary depending on a number of different factors. The second that the test is exposed to the outside world, you run the risk of contaminating its contents and creating a manipulated result that may not be reflective of your current health state.In general, studies have found that the devices would miss between 20% and 81% of positive cases in the different settings - 20% at the Test and Trace centre, 29% in the city-wide mass testing, and 81% in the university screen testing. Data suggests that the further away from a controlled environment, the less accurate the test becomes, which can have damaging impacts if a positive reaction is not picked up. However, this can be hard to measure.
Regardless, to try and limit your chances of a failed test, there are some easy steps you can take to create a sterilised environment. You should wash your hands and the surrounding area where you plan to take the test before opening the box. This will remove any debris that could enter the sample tube and reduce the chances of contamination with outside influences, as well as helping you to prepare yourself to start the test. Besides, by cleaning the surrounding area you can make a good surface to work upon with plenty of room for the testing kit sections, which can also help you to be more prepared and make the test more accurate.
Studies into the accuracy of commercially produced rapid antigen tests found that of 100,462 nose or throat samples, Covid-19 was confirmed in 16,822 of these samples. The study concluded that in people with Covid-19, antigen testing correctly identified an infection in 73% of people with symptoms, compared to 55% of people without symptoms. This would suggest that both rapid antigen tests, and lateral flow tests by association, have a much higher percentage of accuracy than previously thought, making them one of the most reliable and accurate methods of Covid-19 prevention and detection.
Do You Need An Emergency Covid Test?
If you believe that you may be suffering from Covid-19 and would like clarity so that you can seek treatment, it’s always best to take a test as soon as possible. Our specialist team is on hand around the clock to provide quality care and services to help get Covid-19 tests to you so that you can start the road to recovery earlier. With our innovative new services and products, we are able to provide you with a unique and speedy service that will help redefine the meaning of ‘customer service’ forever.
Our mission is always to reinvent the modern way of taking and receiving Covid-19 tests and provide a service which is reflective of modern-day issues and solutions. We have always been proud to be able to say that our service has catered to 15,000 travellers to date, with many more expected to come in the following years.For more information on how to reach us and order your tests today, you can contact Official Rapid Tests using our online form for the quickest responses and swift support from members of our team. Alternatively, you may choose to book an appointment for consultation either in person or over the phone to discuss your options and what may suit you best. Whatever you choose to do, we have no doubt that you’ll find what you’re looking for with us.