Can’t over rely on PCR tests, say health experts

 

An over reliance on PCR tests to detect Covid-19 may not be an effective strategy to fight the pandemic, say experts.

PETALING JAYA: Two public health experts have urged authorities to exploit the advantages of different Covid-19 tests to maximise the chances of success in limiting transmissions.

They referred to recent research published in the medical journal The Lancet that says an over reliance on PCR tests to detect Covid-19 may not be an effective strategy to fight the pandemic.

PCR is short for “polymerase chain reaction”. PCR tests are highly sensitive and accurate in detecting Covid-19. They can pick up remnants of the virus weeks after the patient has been cleared and is no longer infectious.

Noting studies showing that patients are typically contagious for only four to eight days, the experts told FMT rapid tests which might be less sensitive but better at detecting infectious people could be effective as tools for stemming transmission.

Dr Sharifa Ezat Wan Puteh, a public health professor at Universiti Kebangsaan Malaysia, said using rapid tests would be a much more appropriate mass screening approach due to their speed and ability to detect people in their infectious window.

PCR tests would be ideal for confirmation, she added.

“From a public health point of view,” she said, “screening those who are possibly infectious is crucial to detect, isolate, treat and release them back into the society once they are considered fit.

“I’d propose screening with RTK-Ag tests and then use PCR only in certain cases.

“If somebody tests negative with the rapid test, but shows symptoms, you use the PCR to see if it’s a false negative. If somebody tests positive, you go to the PCR test to double check.”

She said “rapid tests are the way to go” in order to test large groups with speed and minimise transmission.

Dr Khor Swee Kheng, a public health specialist who holds fellowships in various institutions, said there must be a balance in the deployment of RTK-Ag and PCR tests.

“An over-reliance on either one is harmful,” he said.

“A testing strategy for Malaysia should utilise both tests, trying to use their respective strengths to offset their respective weaknesses.” - FMT