Testing for COVID-19
Widespread population testing is essential for controlling the SARS-CoV-2 pandemic, so the economy can re-open and life can return to normal.
Identifying and isolating those with the virus helps to avoid spread of the virus. Slowing the rate of new infections reduces the number of daily cases, and lowers the overall number of cases.
Effective testing and quarantine measures help ease the pressure on health services, which can quickly become overwhelmed as demand surges for respirators and other critical lifesaving equipment.
Types of Tests
Two kinds of tests are available for COVID-19: Viral tests and antibody tests.
Viral tests diagnose a current infection.
Antibody test screen for a past infection. Antibody tests may not detect current COVID-19 infection because it can take 1–3 weeks after infection for your body to make antibodies. A positive antibody result may mean that person is protected from getting infected again. It is not clear how much protection the antibodies might provide or how long this protection might last.
Viral Tests RT-PCR (Real-Time Polymerase Chain Reaction)
RT-PCR tests detect the viral RNA in a sample. They reverse-translate the viral RNA to make cDNA which is then amplified by PCR, and the amplified product is then detected and interpreted for a positive or negative result.
This test can be performed on various samples (nasopharyngeal or oropharyngeal swabs), however recent evidence shows that saliva provides the most accurate results.
If you test positive for COVID-19 by RT-PCR
- Inform anyone you have been in contact with
If symptoms develop go to How is Covid-19 treated?
If symptoms worsen, especially if you have difficulty breathing, seek medical help immediately.
If you test negative for COVID-19 by RT-PCR, you probably were not infected at the time your sample was collected. However, that does not mean you will not get sick. The test result only means that you did not have detectable amounts of SARS-CoV-2 viral RNA at the time of testing.
You might test negative if the sample was collected too early in your infection and test positive later when symptoms appear.
Remember, you can also be exposed to SARS-COV-2 after the COVID-19 RT-PCR test and get infected then.
COVID-19 Antibody Tests
COVID-19 antibody tests can tell you if you had a past infection, but might not show if you have a current infection because it can take 3-10 days after infection for your body to make antibodies.
There are different types or 'classes' of antibodies. IgM antibodies are a sign of acute infection and are produced by B-cells, as a first line of defence following infection. IgG antibodies are produced by the humoral immune system and are the second line of defence following infection. An IgG antibody response is associated with protective immunity. IgA antibodies are detected in saliva while IgM and IgG antibodies are found in blood.
The immune system is very complicated and other things like T-cells act to protect individuals from infection, which these tests don’t measure.
Having antibodies to the virus that causes COVID-19 might provide protection from getting infected with the virus again. If it does, we do not know how much protection the antibodies might provide or how long this protection might last.
If you test positive for COVID-19 by an antibody test, it means that you may have previously been infected by SARS-CoV-2 and your body has made antibodies to fight the virus.
If you are IgM or IgA positive
- Immediately get a RT-PCR test to see if you are still contagious
If you are IgG positive it means you are unlikely to be infectious and may be protected for a time from future infection
If you test negative for COVID-19 by an antibody test, it means you do not have detectable levels of antibodies against the virus.
This may be because you have not been exposed to the virus, but it could also mean that your body has not had time to react to the virus and produce antibodies.
This is the reason why the regulators do not recommend using COVID-19 antibody tests for DIAGNOSIS.
Another concern about COVID-19 antibody tests is the varied immune response seen between individuals to different viral proteins (or antigens). Our laboratory amongst others has demonstrated that some RT-PCR COVID-19 positive individuals react to the SARS-CoV-2 Nucleocapsid protein, and others only react to the SARS-CoV-2 Spike protein. For this reason, to avoid false negative results, it is recommended that COVID-19 antibody tests contain both SARS-CoV-2 Nucleocapsid antigen and Spike (Receptor Binding Domain) glycoproteins.
There may be some cross reactivity of antibodies produced following infection by other coronaviruses apart from SARS-CoV-2. In order to minimise false positive results in COVID-19 antibody tests, a specific region of the Spike glycoprotein that is only found in SARS-CoV-2 is recommended. This region is called the 'Receptor Binding Domain', and is used alongside SARS-CoV-2 Nucleocapsid antigen in the BioSmart COVID-19 antibody screening test.
How is COVID-19 treated?
Current treatment is symptomatic.
You can take paracetamol and or Ibuprofen for fever and aches and pains.
If you have a productive cough, you can take a cough syrup.
If you are battling to breathe, you may need oxygen from a clinic or hospital.
Antibiotics do not work for COVID-19, but if you develop a secondary bacterial infection, your doctor may prescribe an antibiotic.
To date, there are no anti-virals that have been shown conclusively to work, but research is continuing in that area.