After False Negative Results, MOH Reviews Covid-19 Antigen Rapid Tests

By Boo Su-Lyn | 10 July 2020

Over 68,000 antigen rapid test kits (RTK) have been run, of which 166 tested positive for coronavirus.

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KUALA LUMPUR, July 10 — The Ministry of Health (MOH) is reviewing the use of antigen rapid tests at airports, after five people with Covid-19 wrongly tested negative for coronavirus.

According to Health director-general Dr Noor Hisham Abdullah, 68,556 antigen rapid test kits (RTK) have been run as of July 7, out of which 166 people (0.24 per cent) tested positive for coronavirus.

“We are studying and reviewing the RTK antigen,” Dr Noor Hisham told CodeBlue yesterday.

The Sarawak Disaster Management Committee (SDMC) said Wednesday that five Covid-19 patients — including a man who did not display symptoms — tested positive on the gold-standard RT-PCR test upon landing in Sarawak, despite earlier testing negative for the coronavirus with the antigen RTK at the Kuala Lumpur International Airport (KLIA) when they returned to their home country from overseas.

Dr Noor Hisham said the specificity of the antigen RTK used at the KLIA and klia2 airports was 100 per cent, but the test’s sensitivity was 85 per cent. He did not reveal the brand of the test.

Sensitivity measures how often a test correctly generates a positive result for people who have the condition that’s being tested for. A test that’s highly sensitive will flag almost everyone who has the disease and not generate many false-negative results.

Specificity measures a test’s ability to correctly generate a negative result for people who don’t have the condition that’s being tested for. A high-specificity test will correctly rule out almost everyone who doesn’t have the disease and won’t generate many false-positive results.

When asked about the procedure of conducting antigen rapid tests, the Health DG said swabs are taken for the antigen RTK and the sample tested with RT-PCR.

“We do not rely on testing but clinical symptoms etc; if symptomatic, will repeat the RT-PCR.”

Bandar Kuching MP Dr Kelvin Yii yesterday expressed concern with the antigen RTK’s inaccuracy, saying that false negative results could inadvertently cause people to be lax in their home quarantine when they wrongly believe that they’re free of Covid-19 infection.

Former Malaysian Medical Association (MMA) president Dr Milton Lum, in his column on CodeBlue, questioned the quality assurance of both the RTK and RT-PCR tests used in Malaysia.

“The Health Ministry has, at the time of writing, not published any data on the quality assurance of the viral Covid-19 tests, in particular, its reliability,” he wrote.

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