If you are considering paying privately for a test for COVID-19 -we hope that our updates may help inform you as to the latest information available, and show that we are continually listening and reacting. The information we have is accurate as far as we know at the time of writing, but we shall be vigilant and will react to new evidence that comes our way, whenever it is credible and validated. There is a lot of debate about the subject of COVID-19 testing, and advice is being modified from a number of authorities on a weekly if not daily basis. You would be forgiven for being confused, and the information received from various scientific quarters if not conflicting certainly carries a risk of being biased towards the particular specialist area of interest of whoever is making the statement – be it public health, virology, immunology, epidemiology or indeed the government.
Looking at testing now, there are basically two groups of tests – tests to show if you have the illness, and tests to show whether you have had the illness.
There is less debate now about diagnostic tests – these are accurate if the sample is correctly collected and the individual is symptomatic when tested. There are a few recognised processes and the one we use is the highly reliable PCR method. When it comes to antibody testing, things are more complicated and controversial. Along with other reputable providers, we have held back from offering antibody testing until we have been satisfied that the tests have an acceptable degree of accuracy. Some processes have been shown to be more reliable than others, and in this particular scenario, the so-called ‘rapid home test’ or lateral flow technique has been shown to be wanting on initial studies. For that reason we are currently not offering any home or near patient testing kits, and are only offering laboratory based ELISA tests at the time of writing, so “home to lab” testing rather than “home testing”. No biological test is likely to be perfect so at some point a decision is made as to what degree of sensitivity (accuracy) is acceptable. And this decision may differ between a government and a commercial organisation. There is a distinction to be made between mass public screening of the type the government is talking about, which is large scale and is aimed to steer short and medium term policy – ease restrictions, send sectors back to work and so forth. It is very important that there is capacity for millions of these tests, and that they are sensitive enough to detect as many as possible to ensure accurate mass data collection. On an individual scale, there are different personal reasons for knowing a result - whilst I will need to be careful about hygiene in general to avoid transmission, I may be able to relax a little knowing I have had the infection and may possibly have a degree of immunity. As this type of testing is on a smaller scale, laboratories can easily scale up now, which is why the test is already available commercially. If the test is a little less sensitive than desired, that may not be so critical – the most likely explanation would be a suboptimal immune response meaning minimal antibodies produced or that the test was taken too soon, or that there was no infection in the first place. A retest could be arranged, less of an impact on an individual basis but a considerably more complicated undertaking on a public scale if tens of thousands of retests are needed.
Over the past few weeks, antibody testing has been increasing all across the UK, USA and Europe on both public and private levels. The National Institute of Health in the USA has launched a 10,000-person study to quantify undetected cases of COVID-19. The National Institute of Allergy and Infectious Diseases has called for 1,000 volunteers, hoping to find people who have antibodies to the new coronavirus, but no known exposure or illness.
Researchers are also still deciding which antibodies their tests should look for. Some antibodies are made early in an infection and go away, usually within a few days or weeks (IgA and IgM decline after 5 days or so), while others (typically IgG) can persist for months or years. IgG is looking to be the preferred candidate, but as already stated it takes time to develop and will probably only become detectable by ELISA testing after at least 14 days. We have opted to test only IgG for consistency and because we believe this will be the gold standard on larger scale programmes.
We are confident that both tests we offer are currently as reliable as any others available, and better than many more. We also keen to ensure the best value for our customers and will ensure the price is competitive. We are fully engaged with the laboratories and know that they uphold the highest standards of testing process, and that they will notify us should there be any changes in direction.
Dr Graham Johnson – Blue Horizon Medicals.
Click here to view our COVID-19 Home Coronavirus Test Kits