Antibody Testing for COVID-19 What’s the Best Option?
21st May 2020
There are two tests that we currently have available to test for Coronavirus COVID-19, the first is the swab test where we can look for the presence of active virus infection by looking for the genetic material contained in the virus. This test is great at picking up whether or not you actually have the virus infection now. So if you have symptoms and signs of COVID-19 infection and you are over 5 years of age you can quite easily access one of these tests through the NHS. How good are they? I would point you in the direction of a paper published this week in the BMJ called “Interpreting a COVID-19 test result”. This paper discusses a sytematic review that puts the sensitivity of RT-PCR (the test that we use to diagnose current infection) at between 71-98%. It is clear that the way that samples are taken also have a significant effect. For example, The sensitivity of this test is 93% if done by broncho-alveolar lavage (suctioning directly from the breathing tubes in an anaesthetised patient) to 72% by sputum, 63% by nasal swabs and only 32% for throat swabs in some cases. The authors of this paper suggest that negative results should be treated with caution and that there is an argument for repeat testing in those that are initially negative because “false negatives carry significant risk”. But there is a much bigger issue here. We are trusting our government and the leaders of our NHS with our safety. We continually hear about being led by the science but the scientific facts are concerning. It is true that the government has a difficult task in managing and controlling the population so that we avoid panic and we minimise the risk of death to the population as a whole. This was the whole flattening the curve concept. This has worked without a doubt but now we enter the phase of having to balance off long term economic instability against deaths. Unfortunately the harsh reality of entering into this discussion is that it will be a mathematical equation. How many deaths can we as a society accept against how quickly should we be getting the economy moving again?
Enter the new IgG Antibody test which tells you if you have had Coronavirus COVID-19 infection. We are all being very careful with our words here, we cannot say that if you have evidence of previous infection that you are immune because we don’t have the evidence for that yet. Even the WHO are side stepping on this. But, based on previous coronavirus infections we are likely to have some immunity. If this is the case then it is possible that those who have antibodies against COVID-19 may have some protection against further infection at least in the short term and possibly longer. If we can identify the presence of those antibodies accurately this could lead to enhancing safety for our population by adding another level of analysis for risk assessment. This leads to the concept of an “immunity passport” for those who are antibody positive. This is something that the WHO are resisting as it may lead to a type of division in society but it is probably inevitable.
Last week the UK government endorsed the Roche antibody test and this was followed a few days later by the Abbott antibody test. The Children’s e-Hospital has been using the Abbott test which is lab based and relatively simple to do by finger prick. Both tests are now endorsed by Public Health England and are run by UK accredited laboratories only. They are highly sensitive (greater than 97.5%) and highly specific (greater than 99.6%). Indeed the Abbott test that we use with The Doctors Laboratory has an internal specificity of 100%. Compare this with the “gold standard” of RT-PCR above and I think there is a serious discussion to be had! Superdrug and Babylon are offering the test at a reasonable price (£69) but our process at The Children’s e-Hospital (as a CQC “outstanding” organisation) is to enhance patient safety, so we have an online medical assessment form that needs to be filled before you get the kit and then a medical review of the results before you get the result. We are reviewing our prices regularly to try and give the best service at an affordable price (currently £79.99) through The Children’s e-Hospital Shop. It will be interesting to see how quickly the NHS will respond. As a private health provider we are able to get ahead of the curve, my personal opinion is that having knowledge of previous Coronavirus infection is invaluable but at the end of the day it is also about personal choice. I keep going on about how well the Germans & South Koreans have done through this crisis and how they have used technology and testing to protect and treat their population. In the UK I feel that we are getting there but it is just oh so slow! It might just be time for us to take a firmer grasp of our own destinies.
The next discussion will no doubt be about hydroxychloroquine, azithromycin and biological treatments but for now remember to take your daily zinc!