COVID-19 testing explained

April 21, 2020

(To watch the full media briefing with sign language interpretation, click here.)


The Centre for Health Protection today said it will not use antibody tests to detect COVID-19 because its current manner of testing is more accurate and cost effective.


Centre for Health Protection Controller Dr Wong Ka-hing made the remarks at a press briefing this afternoon when responding to enquiries about whether the Government plans to extend coronavirus testing to include antibody tests.


Dr Wong explained that while medical experts have raised the idea of using antibody tests to detect one’s immunity response to the virus, the antigen test, also known as the polymerase chain reaction (PCR) test, is the most effective way of detecting the presence of coronavirus in the body.


“Regarding the coronavirus testing, I highlighted the antibody test because actually that’s been going on for a while, it’s not just in the recent few days. There has been interest in whether the testing can be extended to (cover) antibody tests which are quite expensive for a viral infection - apart from the PCR tests, which have been the gold standard as of now for the testing of coronavirus.


“This has been raised by a colleagues, including from the medical community, from private doctors, etc to address this issue of some antibody tests for the coronavirus that has been circulating in the community, not only in Hong Kong, but also overseas.”


Dr Wong also noted that antibody testing is neither validated nor standardised.


“I would like to point out that at this point in time for the diagnosis of coronavirus infection, it remains PCR tests, not antibody tests because it’s not as timely as the PCR tests (at revealing) positive (results) within the infection.


“And also, up till now, we understand that the sensitivity, in particular the specificity of the antibody or serology tests for the coronavirus have not been validated or standardised.”

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