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Testing for Covid-19

Living in a world that is currently dominated by Covid-19; locally, nationally, internationally, and at almost every turn, you may be wondering how it is that we can so easily ‘test’ people for the virus, and determine the daily caseload, right across the globe?


Well I’m glad that you asked! In today’s piece I thought it might be useful to address this process which, like so many things in our modern-day, busy, technical lives, is seemingly ‘glossed over’ as if it’s just expected that we would have a test for it. The fact is that several things must come together in order to successfully identify a viral infection in a mere swab of mucous taken from the back of your airways – and to do so within 24-48 hours of sampling. Moreover, the track-and-trace approach to containing the spread of disease relies heavily upon both the accuracy, and the rapidity, with which a test can be performed.


So, what are these factors?


Well essentially, we need a reliable, reproducible method of both obtaining a specimen, then screening it, to detect components of the virus, i.e.

  • Effective specimen collection

  • Techniques for DNA isolation

  • Knowledge of key genetic markers

  • Screening for sections of genetic code

Sounds easy, but there’s a lot to it and thankfully we’ve made enormous progress over the last 100 years.


Effective specimen collection:

If you’ve been tested for Covid-19 then you’ll appreciate that it’s quite an uncomfortable process collecting the specimen – usually via a long cotton-tip swab guided to the back of your nose and throat. You may have wondered why it must be collected from there, rather than the more acceptable methods you might see on TV, where a person’s DNA is obtained by swabbing the sides of their cheek?


It’s a fair question but, given that we’re testing for the virus, then we need to isolate the viral DNA, not yours! Corona-viruses (like most cold and flu bugs), fall into the category of ‘rhinoviruses’ which means that they tend to inhabit the back of the airways, i.e. back of the nose and throat. So, if we’re looking to obtain a specimen that has viral DNA in it for testing purposes, then it makes sense to obtain that specimen from the back of the airways.


Techniques for DNA isolation:

Once we have a specimen to test, the next step is to isolate some DNA – the building bl