But the Consumer Council received a total of 48 complaints about RAT kits between January 14 and March 8, of which 19 were related to late or non-delivery of goods, 13 to certification issues, while the rest concerned sale practices, expiry dates and spurious goods.

Council chief executive Gilly Wong Fung-han said the prices of the kits mentioned in the complaints varied from HK$18 (US$2) to HK$120, with 37 cases involving purchases made online and 11 bought in-person.

“An abundance of RAT brands from different places are available on the market and online,” she said. “People may wonder which ones have international accreditation and are more accurate, with a lower chance of getting a ‘false negative’ or ‘false positive’.

“Such information is crucial for consumers yet it is complex and difficult to understand.

One complaint featured a consumer who had ordered four boxes of test kits online for a retail price of HK$222, from a brand claiming to be certified by the European Union (EU).

However, the buyer could not find the product in the EU’s “common list of Covid-19 rapid antigen tests” list.

In a separate case, a consumer had ordered 80 RAT kits online for a total price of HK$6,500, but later found the products would expire in four months.

Council chairman Paul Lam Ting-kwok said to cope with the surging demand for RAT kits, the watchdog had rolled out a search tool to allow consumers to check which brands fell within five lists showing tests approved by the various authorities.

Users simply need to enter the manufacturer or brand name into the search engine to get a result.

He said the World Health Organization (WHO) recommended RAT kits should adhere to a sensitivity of at least 80 per cent and specificity of at least 97 per cent. The former concerns the test’s ability to pick up on positive results, while the latter reveals whether it can accurately identify negative results.

“The Hong Kong government has accepted five specific lists of RATs. Two have been compiled by the government, with one under the medical devices admin control system and the other a list of brands given for free to some specific groups. The other three lists are approved by mainland China, the US and the EU,” he said.

“The best and easiest way for consumers to ascertain whether a particular RAT is effective is to check whether it falls within any of the five lists.”

Lam said in cases where a particular brand was not on any of the lists, it did not necessarily mean it was ineffective. “It simply means that consumers would need to make further inquiries into the particulars of the product,” he said.

He added that consumers should not be misled into thinking a product’s price was proportional to its effectiveness.

“As to whether a particular RAT is effective, I do not think it has anything to do with its price. There is no necessary logical connection between prices and effectiveness,” he said.

Lam also said there was no shortage of RAT kits in the local market and called on Hongkongers not to hoard supplies or panic buy kits.

“While the price range of RATs on the market fluctuates very quickly, there’s no reason for us to believe that there would be a sudden or very significant increase in prices largely because there’s simply no shortage of supplies,” he said.

The chairman said the list being implemented in Hong Kong was a voluntary initiative for traders based on a framework known as the medical device administrative control system under which listed products met requirements of safety, quality and performance without requiring brands to obtain certification.

“This is the system that we need to work with for the time being. So I would urge traders to make the best use of the existing system to assist consumers with identifying goods and products that fulfil the government’s requirements,” he said.

Lam added that it would be ideal to have some sort of mandatory regulation to verify the authenticity of the medical devices.

Watchdog chief executive Wong called on consumers to check if the product was reliable before making any purchases.

“When they buy the test kits they really have to go for more credible shops and also be mindful of all the tips we have provided,” she said.

“When you make purchases online, don’t buy a large quantity of the kits because you don’t know the expiration date. Secondly, if you buy a kit from a physical shop, it’s very important to check the packaging, expiry date and the manufacturer.”