How antibody testing works

Government has announced that it will roll out, antigen tests for SARS-CoV-2 detection at all ports of entry in South Africa with immediate effect.

Government has announced that it will roll out, antigen tests for SARS-CoV-2 detection at all ports of entry in South Africa with immediate effect.

Published Jul 14, 2020


DURBAN - With all the talk about Coronavirus testing in the news, it's not surprising that there's confusion about tests and how they differ. In his address on Sunday, President Cyril Ramaphosa said the country has introduced antibody testing for community-based surveillance to estimate the population that has been infected with this virus.

An antibody testing determines whether you had Covid-19 in the past and now have antibodies against the virus, while a test to diagnose Covid-19 determines if you currently have the disease.

Several doctors have described the antibody testing as a possible "missing weapon" in the fight against the virus.

“This type of test is affordable and easily scalable on robotic instruments that already exist in most laboratories, giving results for thousands of tested people within a few hours. Exactly this type of test is needed to define the important public health question of what is the real number of people infected with SARS-CoV-2, and to better estimate how serious this infection is by allowing the calculation of the case fatality rate (CFR),” said virologist Prof Eftyhia Vardas.

A Covid-19 rapid antibody test, which will cost less than R300 a unit, has been approved for use in South Africa - but it is not yet available privately or to the general public.

The South African Health Products Regulatory Authority (SAHPRA) has given the first licence to supply the rapid antibody test in South Africa to Johannesburg-based company Tip Top Trade.

Chairperson of the Covid-19 ministerial advisory committee, Professor Salim Abdool Karim says the tests will be available to the public soon.

"Some of them are laboratory-based tests and others are clinic-based tests. We do not have any home-testing that we are looking at - it is only facility-based," he said.

Antibody testing, also known as serology testing, is done after full recovery from Covid-19. Eligibility may vary, depending on the availability of tests. A health care professional takes a blood sample, usually by a finger prick or by drawing blood from a vein in the arm.

Then the sample is tested to determine whether you've developed antibodies against the virus. The immune system produces these antibodies — proteins that are critical for fighting and clearing out the virus.

If test results show that you have antibodies, it indicates that you were likely infected with Covid-19 at some time in the past. It may also mean that you have some immunity. But the World Health Organization cautions that there's a lack of evidence on whether having antibodies means you're protected against reinfection with Covid-19.

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