Home test kits to detect Covid-19 have their limitations, cautioned Professor Wang Linfa, director of the emerging infectious diseases programme at Duke-NUS Medical School.

"I know the general public thinks it's great to have a home kit, but... I'm convinced you can never produce a home kit as accurate, as sensitive as a lab-based test," he said yesterday.

A recent attempt in the UK to use such kits on a mass scale fell flat, after the authorities announced that at least 3.5 million such kits were too inaccurate to be used.

Earlier this month, the Health Sciences Authority (HSA) removed the online listings of a number of illegal test kits with inherent limitations which might have resulted in incorrect or misleading findings.

HSA said: "Self-directed use of such unapproved test kits by consumers can lead to a false sense of security and risk the spreading of Covid-19 unknowingly due to false negative readings, or result in delay in seeking appropriate treatment."

Prof Wang said there might also be operational issues associated with such tests.

He said: "In a finger prick test, when you take blood and put it on the apparatus, do you do it yourself, or ask your brother, or your mother, or your grandfather to do it?

"Because if that person's hand is shaking, you will have a drop of blood in the air, and you may infect the person trying to help you if you're actually (infected)."

Prof Wang acknowledged home test kits may still have their uses - such as mass testing to see what proportion of a population is infected - but felt that it might not be helpful in other situations, such as letting individual people know whether they are immune to the virus.

"They have their uses. But you have to (know) what question you are asking," he said.