COVID-19 antibody testing | 2 min read

The national Department of Health (DoH) has confirmed that antibody testing is now legal in South Africa.  Antibody testing determines whether you had COVID-19 in the past and now have antibodies against the virus.  Antibody testing, also known as serology testing, is usually done after full recovery from COVID-19.

Herewith the guidelines from the DoH for the use of antibody testing:

  • The available evidence suggests that the sensitivity of antibody tests (using any type of antibody) is too low in the first week since symptom onset (period of greatest infectiousness) to have a primary role for the diagnosis of COVID-19. It is thus recommended that PCR testing remains the modality for acute clinical diagnosis of COVID-19.
  • A negative antibody test result does NOT reliably rule out prior SARS-CoV-2 infection. Possible reasons for this include:
    • Insufficient sensitivity of the antibody test.
    • Testing within 14 days of symptom onset. If it was asymptomatic infection, one would not know what the infection date was and whether it’s in that window.
    • Some patients may not form detectable antibodies, especially following asymptomatic SARS- CoV-2 infection.
    • Waning of antibodies over time, and as soon as 1-2 months in asymptomatic or mild cases.
  • A positive antibody test result does NOT reliably prove prior SARS-CoV-2 infection. Possible reasons for this include:
    • Insufficient specificity of antibody test.
    • Cross-reacting antibodies, e.g. those directed against other human coronaviruses.
  • The detection of antibodies may not correlate with immune protection and a positive antibody test result therefore should not be regarded as proof of immunity and must not be used to reduce or abandon protective measures. The issuing of an “immunity passport” or “immunity certificate” based on a positive antibody test result is not recommended in South Africa or by the WHO.  The antibodies detected by different tests do not necessarily represent neutralising antibodies that are assumed to be the best measure of antibody-based immunity and protection against infection and/or disease.
  • Even if you test positive for antibodies, do not assume protective immunity. Please continue following all precautionary measures already in place (this also applies to those who have previously tested positive on the PCR test and have recovered).

 

Source: SA National Department of Health

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