Rapid Antibody Tests Can’t Diagnose Covid-19: Health DG

A negative antibody test result doesn’t guarantee that the person is free of Covid-19 infection, says Dr Noor Hisham Abdullah.

KUALA LUMPUR, May 11 — Antibody rapid test kits (RTK) are not suitable for Covid-19 diagnosis, the Ministry of Health (MOH) reiterated today as workers seek coronavirus screenings before returning to work.

Health director-general Dr Noor Hisham Abdullah said MOH uses two types of antigen tests to detect the novel coronavirus — the gold-standard RT-PCR test or the antigen RTK.

Both tests require nose and throat swabs taken by trained professionals wearing suitable personal protective equipment (PPE), as well as laboratory equipment like biological safety cabinet while processing test samples.

“Meanwhile, the serology antibody RTK that uses blood samples from finger-prick procedures cannot be used for diagnostic tests,” Dr Noor Hisham said in a statement.

“This is because the presence of antibodies cannot confirm active infection. A negative antibody test result also doesn’t guarantee that the tested individual is not infected by Covid-19.

“However, antibody RTK can be used to conduct Covid-19 sero-prevalence studies in the community or in targeted populations (like workers’ groups). This is in line with the World Health Organization’s (WHO) recommendations that antibody RTK can be used in surveillance activities and epidemiological research.”

The Health DG also reiterated WHO’s stand that there is no evidence so far that people who have recovered from Covid-19 and produced antibodies are immune from a second infection.

PCR tests detect active coronavirus infection and hence, are used to diagnose Covid-19, but lab results take 24 to 48 hours. Rapid antibody tests, on the other hand, require a simple pin-prick procedure to draw a drop of blood, but they can only detect a previous coronavirus infection as it takes the body several days to over a week to produce antibodies in response to the virus.

MOH’s Private Medical Practice Control Section (CKAPS) told private clinics last week that the ministry currently only recognises PCR tests as a Covid-19 screening method to prevent medicolegal issues, amid the Social Security Organisation’s (Socso) coronavirus screening for workers.

Socso then decided to cancel the rapid antibody tests under its Prihatin Screening Programme (PSP) that the social security fund had initially planned for private general practitioner (GP) clinics to use for workers’ Covid-19 screening. Socso also said Saturday that the Covid-19 test is compulsory for foreign workers in the construction sector or those working in coronavirus red zones only.

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