Along with my investigation of the SARS-COV 2 Virus and how it infects humans I also need to understand how the current detection tests work. Let’s get a few things straight first though. The current [early May] testing regime in the UK is pathetic and nowhere near enough to be able to track where this virus is going. Also, let’s be clear about this, Covid-19 is not a mild cold or flu. Some people won’t suffer very much with it but others are dying. I read a tweet from a 30-ish year old person saying that it felt like they couldn’t breathe for three days. I don’t want to experience that.
There are two main types of test that can be done for the virus. At the moment, in the UK these are done when you first show symptoms. That way, if you have CV-19 you can isolate and if you haven’t then you can go about your business. This is a method for reducing the transmission of this killer disease.
The first test detects the virus itself. This can be done by taking material from easy to reach places on the human body. For this test to work you need to have been infected for a few days already and for the virus to multiply in your body to get to the nose or throat. As the infection continues this test becomes less effective because the virus stays largely in the lungs and reduces elsewhere. As this virus is RNA only and the test can only detect DNA there is some chemistry magic to be done first to convert the RNA and then all DNA in the sample is copied. Finally more chemistry is done to detect the DNA version of the RNA of the virus. This can take two hours to two days. All it tests if whether you have the virus in your nose or throat at that time. It doesn’t mean you are clear. There can be errors.
The second type of test detects the body’s response to the infection. It detects the cells in our blood that fight the virus. By definition this test needs to be done once the infection is being fought. There are two main types of antibody that can be detected and the amounts of those in the blood vary over time. I found this lovely graphic on Wikipedia:
It’s quite hard in these times to find decent correct information on the web about what is going on. I’ve been avoiding newspapers and other traditional media and mainly sticking with podcasts where the presenter / interviewee is qualified or Wikipedia. The World Health Organisation website is brilliant too and has the level of detail I wanted.
My next communication might be about the UK Govt response to this crisis. But I’m not sure I’m willing to enter that pit of desperation yet.