Everything you need to know about COVID-19 testing
Please Note: This article discusses COVID-19 testing in general. For more information on the private coronavirus tests available from Your Sexual Health, please visit our COVID-19 product page.
COVID-19 continues to grip the world, but as the UK struggles to increase its coronavirus testing capacity, we thought it was important to answer some of the key questions surrounding coronavirus testing.
What are the different types of Covid-19 test?
There are two broad categories of COVID-19 tests that currently exist, PCR tests and antibody tests.
PCR Testing
PCR testing is used to see whether a patient has the virus at the time they are tested. The majority of tests that are being used both in the UK and across the globe are PCR tests. These tests use a nasopharyngeal swab sample taken from the nose and the throat which is then tested in a laboratory for signs of the virus RNA.
They identify the presence of the SARS-CoV-2 nucleic acid and diagnose whether the patient currently has the virus in their body. By detecting the viral RNA, they are able to diagnose COVID-19 in the very early stages of infection.
Antibody Testing
Where PCR tests identify the virus itself, antibody testing identifies your body’s response to the virus. These tests can say whether someone has had COVID-19 in the past. They work by identifying the presence of antibodies created when your body fights off the virus.
These tests require a blood sample, usually delivered through a finger prick. Many COVID-19 antibody tests that are currently available are instant tests that can offer results within 15 minutes of a sample being taken. In the UK, these are only safe to be carried out by a medical professional.
Most antibody testing will look for both IgM and IgG antibodies. [1]
- IgM antibodies appear early on in an infection
- IgG antibodies show up later on following infection, usually after you’ve recovered.
These are currently available as a laboratory test, but only one that identifies the IgG antibody. However, at this moment in time no rapid test has been approved by Public Health England due to question marks over their accuracy and the World Health Organization has warned countries against using them. [2]
How do you get a Covid-19 test?
The UK is not currently testing for COVID-19 amongst the general public, but people can still get tested by going to a private company such as Your Sexual Health. Many private companies are currently offering PCR tests that use the same test assay as those used by the NHS.
Your Sexual Health currently have COVID-19 PCR Home Test Kits available for £249 which allow you to collect the sample at your own home before posting it to the laboratory.
What happens if you test positive for Covid-19?
If you test positive for COVID-19, it doesn’t affect your prognosis because there is currently no cure for the disease. It does however, allow you to protect others from infection.
If you test positive, you should self isolate for seven days after your symptoms first appear, unless you still have symptoms after 7 days, in which case you should continue to self isolate until your symptoms disappear.
Those in your household must self isolate for 14 days after you first showed symptoms. For full advice on what you should do if you show symptoms or test positive for coronavirus, visit the government’s coronavirus response page.
By taking a test that returns negative, you will know that you pose no danger to your family, friends or colleagues, although social distancing measures should still be observed.
How can coronavirus testing help?
When it comes to COVID-19, testing plays a vital role in how the global community deals with the virus.
Prevent the spread
Testing is highly effective at preventing and restricting the spread of COVID-19 as it allows those who have the disease to be effectively isolated. Countries that have tested a higher percentage of the population (such as South Korea and Germany [3] ) have seen a much slower spread of the virus, partly thanks to their ability to contain cases, including those that are asymptomatic.
Elsewhere, a study in Italy showed that testing the entire community completely eradicated the virus from the town. [4] The World Health Organization (WHO) itself has said that the key to containing the virus is to “test, test, test”, [6] but at present many countries are struggling to source enough tests to make the desired impact.
For medical reasons
Although there is no cure for COVID-19, testing helps doctors understand the disease that they are dealing with and helps them manage symptoms more effectively. If a patient presents in hospital with breathing difficulties, it’s helpful for doctors to confirm it’s COVID-19, as other causes could be more easily treated with medicines.
Establish trends within the community
The data gained from both antibody testing and PCR testing can tell us more about how the virus behaves and the dangers it poses for various sections of the community.
As well as helping contain the virus, effective and widespread PCR testing can help the medical profession understand risk factors of the disease overtime, enabling them to be more proactive in their treatment. [6]From an epidemiological point of view, it can help identify whether social distancing measures, such as closing schools or public transport are having a positive effect.
Antibody testing can offer the same kind of data, but more retrospectively and without the primary benefit of containing the virus. It will help identify risk trends, just like PCR testing, but this form of testing will really be useful if the antibodies are shown to offer long term immunity.
Identify if people are immune (hopefully)
COVID-19 antibody tests can tell if a person has been infected by the virus in the past. They work by identifying the presence of antibodies in the blood that are created by your body when it fights off the virus. In theory, if a person has antibodies in their system they would have some level of immunity to COVID-19 infection in future.
This comes with a major caveat though: COVID-19 is a new disease and we have very little knowledge over how it will behave over a long period of time. [7]As a result we have limited knowledge about how effective antibodies will be or how long they will survive in our bodies. Some viruses, including flu, have the ability to mutate around antibodies into different strains each year, limiting the positive effect of antibodies and consequently vaccines.
However, although those who test positive and recover should not ignore any government advice at this stage, many virologists and health professionals are taking confidence in the way antibodies behaved in the 2003 sudden acute respiratory syndrome (SARS) outbreak. Many of those who survived the outbreak still had the antibodies to fight the disease years after infection. [8]
References
- WebMD. Antibody Testing for COVID-19.
- BBC News. 18 April 2020. Coronavirus: Double warning over antibody tests.
- The Conversation. 3 April 2020. Coronavirus: Why is Germany’s fatality rate so low?
- The Guardian. 18 March 2020. Scientists say mass tests in Italian town have halted Covid-19 there.
- World Health Organization. 16 March 2020. WHO Director-General’s opening remarks at the media briefing on COVID-19
- Science Media Centre. 1 APRIL, 2020. Expert comments on different types of test for COVID-19.
- British Society for Immunology. 14 March 2020. BSI open letter to Government on SARS-CoV-2 outbreak response.
- Scientific American. 10 April 2020. What Immunity to COVID-19 Really Means.
