A negative antibody test does NOT mean you are in the clear for Covid-19. To check whether you have an active COvid-19 infection you must undergo a PCR (nasal swab) test.
Two Makhanda residents separately underwent Covid-19 antibody tests at a private facility. Both tested negative. Both left the test venue relieved, believing this meant they did not have Covid.
Both were wrong.
They continued to experience the symptoms that made them seek a diagnosis in the first place, and so underwent nasal swab (PCR) tests. Both subsequently tested positive for Covid-19.
If your Covid antibody (serologic) test comes out negative, that does not mean you are in the clear for Coronavirus.
What Coronavirus tests are usually done in Makhanda?
Antibody (serologic) test: they prick your finger for a blood sample and after 10 minutes, pink and/or blue lines come up on a test strip.
PCR (molecular) testing: they stick a cotton swab up your nose or at the back of your throat to get a mucus sample. Those results take anything between 24 hours and a week.
What is the antibody (serologic) test good for? ‘Serologic testing’ detects antibodies against a virus. It measures the amount of antibodies remaining in your body that were produced by your body to fight an infection. In this way, antibody testing detects if a person has previously been infected by SARS-CoV-2. – Source: WHO
What is the antibody test NOT good for? Antibody tests should not be used to diagnose a current COVID-19 infection. An antibody test may not show if you have a current COVID-19 infection because it can take 1–3 weeks after infection for your body to make antibodies. – Source: Centre for Disease Control (CDC).
What is molecular testing for?
‘Molecular testing’, including polymerase-chain reaction (PCR) testing, detects genetic material of the virus and so can detect if a person is currently infected with SARS-CoV-2. – Source: WHO
If you want to know whether you are currently infected with Covid-19, you need to undergo a PCR (nose or throat swab) test.
WHAT CLICKS SAYS ABOUT COVID-19 ANTIBODY TESTING
Grocott’s Mail asked Clicks, which offers Covid-19 antibody (serologic) testing at its in-house clinics, how they make sure clients understand what to use the antibody test is for and what the results mean. Clicks chief store operations officer Sedick Arendse responded as follows:
A COVID-19 antibody test is a blood test (also known as a serological test) that is used to test for the presence of antibodies by locating the proteins or antibodies that an immune system makes in response to the COVID-19 virus.
The COVID-19 antibody test is useful to determine if the patient may have had symptoms of COVID-19 in the past but did not then test for the virus; if the patient may have been exposed to the virus due to contact with an individual either suspected of being infected with the virus or who has tested positive for the virus. Some patients who had the virus in the past may have been unaware that they were COVID-19 positive because they were asymptomatic and the antibody test will be able to confirm their past positive status based on the presence of the antibodies.
The COVID-19 antibody test checks for antibodies that our immune system produces in response to the coronavirus. The presence of IgG* antibodies on the test can tell you if your immune system has ever had to fight off COVID-19. These antibodies usually appear in your blood 2 weeks after you recover from the virus. If you test positive for these antibodies, you will you know for certain that you had the virus.
We also asked what training Clicks staff undergo that qualifies them to conduct the antibody (serologic) test accurately, as well as advise patients correctly; what quality control Clicks exercises over the practices at its clinics, including Covid antibody testing and what ongoing training and support is provided for clinic staff.
Sedick Arendse responded as follows: The nurses in the Clicks clinics are all professional Nurse Practitioners registered with the SA Nursing Council. In preparation for the roll-out of COVID 19 antibody testing, all of our nurse practitioners underwent training on information to be provided to the public and on how to conduct the testing in compliance with the published protocols. This training is supported by the Pharmacist in the store and further augmented by our refresher courses.
* Explanation (Source: WHO: IgG antibodies are part of the body’s immune response to a virus, known as the adaptive response (or Stage 2): B CELLS (Antibody response: start day 6-8) • produce antibodies that are specific to that virus. • IgM antibodies are produced first and disappear after a few weeks. • IgG antibodies are produced at the same time or 2-3 days later, and levels usually remain for months or years.
Diagram showing the immune response to viral infections. Source: World Health Organization
FOR FURTHER READING:WHO answers questions about Covid-19, serology, antibodies and immunity.
