There is a lot of talk about COVID testing at the moment, especially for those wanting to travel abroad. To get a good understanding of the different types of tests available it is useful to have a little understanding of the structure of the coronavirus SARS COV-2 – which is the virus that causes the COVID-19 infection.
The coronavirus is a core made up of nucleic acid (which makes up its genetic code) in the form of RNA. This core is then surrounded by an envelope (or coat) that contains various proteins. Protein spikes protrude from this envelope, and these attach to the cells of the human respiratory tract.
So, the COVID-19 testing currently available is focused on detecting either:
- The RNA (nucleic acid) – can be detected by a PCR test
- The surrounding proteins – can be detected by a rapid lateral flow test
- The human being’s response to the virus – is detected by the antibody test
The PCR test is aimed at detecting the nucleic acids that make up the coronavirus’s genetic code. These tests are normally carried out in a laboratory setting and are swab tests completed up the nose or in the throat.
PCR tests are very sensitive and so are able to detect very tiny amounts of RNA (nucleic acids) and so they are the best test available for seeing if someone is currently infected with the virus.
People who are infected with COVID-19 tend to find that PCR testing picks up their infection and gives them a positive response a day or two before any symptoms show. They will also continue to test positive for some time after symptoms show as well.
Advice is changing rapidly regarding what you should do if you test positive though, so it is a good idea to keep an eye on the NHS website to make sure you know the most current advice.
Is PCR Testing accurate?
PCR testing is the most accurate test when it comes to detecting the virus in people who are already infected. If an employee has symptoms that suggest they have the virus, and their results of the PCR test are positive then they are likely to have the virus. If they have symptoms that suggest they have the virus but the test is negative, then it may be a good idea to wait 48 hours and test them again to see if the result changes.
Rapid Lateral Flow Testing
Rapid lateral flow testing is the most common form of COVID-19 testing at the present time, as they do not need a laboratory to give the results and so the results can be given in as little as 30 minutes.
Lateral flow tests cannot detect RNA, instead, they are looking for proteins from the virus through the use of a nose or throat swab which looks similar to a pregnancy test.
The rapid lateral flow test is very different from the PCR tests in that it is not suitable for diagnosing people who have symptoms of coronavirus. It is aimed at those people who don’t have symptoms but are infected, and so otherwise may be missed.
Is rapid lateral flow testing accurate?
Rapid lateral flow tests are not as accurate as PCR tests. They are just a more convenient way to pick up people who don’t have symptoms of coronavirus, but who are suffering from it.
If you take an LFT test and receive a negative result then this does not mean that you are not potentially infected with the virus, and so you should continue to take the usual precautions to prevent the spread of the virus, including wearing a mask, social distancing and practising good handwashing techniques.