Three other victims called a hotline set up by the Centre for Health Protection and said that they have developed symptoms. Their condition was unknown, while the 12 others were in stable condition.

Authorities on Thursday said they had not ruled out the possibility of unlicensed medical practices and issued a warning urging those who had received the treatment at the Lai Chi Kok branches, located inside the Hop Hing Industrial Building and Alexandra Industrial Building, and developed symptoms to seek medical attention immediately.

A centre spokesman on Thursday said the treatment involved four to five injections and the women had developed a rash, induration and abscesses, a day to a few weeks after the procedure.

The five women who received the injections between June and August sought medical treatment. Two have been admitted to hospital, while one has been discharged. The five and the other seven patients reached through contact tracing are in stable condition.

Samples confirmed the presence of Mycobacterium abscesses, a type of bacteria commonly found in water, soil and dust, which can contaminate medications and medical devices, according to the centre.

The infection is typically caused by injections with contaminated substances or invasive medical procedures with unclean equipment. Infected skin is usually red, warm, tender, swollen, or painful, with possible purulent discharge or induration.

The joint investigation aims to determine the qualifications of staff who administered the injections and whether unregistered pharmaceutical products or unlicensed medical practices were involved.

Authorities also inspected Gals Glam Beauty’s two other branches – one in Wing Hong Centre on Wing Hong Street in Lai Chi Kok, and another at I Do Centre on Nathan Road in Prince Edward.

During the raid at the Lai Chi Kok branches on Thursday, a 36-year-old woman was arrested on suspicion of illegal possession of unregistered pharmaceutical products for the purpose of sale or distribution and illegal possession of a Part One poison, a police spokesman said. A day earlier, a 27-year-old woman at the Prince Edward branch was arrested on suspicion of committing the same offences.

Both the 36-year-old and the 27-year-old were released on bail and must report back to police in December and February, respectively.

The regulation of medical beauty services first came under the spotlight in 2012, when three women fell seriously ill after receiving contaminated blood products – promoted as a way to improve immunity – at DR group. One woman later died.

The incident prompted the government to review the regulation of high-risk medical beauty procedures and require registered doctors to perform certain ones.

Health authorities proposed a bill to restrict the use of medical devices in cosmetic treatments in 2017, but it was not brought to the Legislative Council.

Currently, beauty parlours that provide medical procedures require day procedure centre or clinic licences and are subject to regulation by the Private Healthcare Facilities Ordinance, which was passed in 2018. But the government has not yet opened the application for clinic licences.

Founding chairman of the Federation of Beauty Industry (HK) Nelson Ip Sai-hung said the sector should have its own statutory regulatory mechanism, with a licencing system tailored for service providers.

“Treating us as healthcare facilities does not work, because our clients are not patients, our services are not entirely medical, and that’s not how we run the business as well,” he said.

Authorities could also set up a separate licencing regime for medical beauty practitioners to ensure quality, he added.

Medical sector lawmaker David Lam Tzit-yuen said it was clear procedures involving injections could only be performed by registered medical practitioners, but it required more than a licence to them.

“The practitioners should have gone through appropriate training, for example, they should be able to decide the amount of injection, identify the contraindications, and explain the expected treatment outcome and side effects,” he said.

“Otherwise, they should not perform the procedure at all. Hong Kong’s legislation is relatively lenient, but the Medical Council strictly prohibits that.”

In addition to stepping up law enforcement efforts against malpractice, authorities should also restrict the use of medical devices, which were not subject to legislation, he said.

The Department of Health adopts an administrative control system for medical devices that is voluntary, allowing manufacturers and importers to list their products, and leaving it up to users to report adverse events.

“But authorities do not require service providers to use those on the list, so the quality, safety, efficacy, usage, maintenance of the medical devices being used on the market were not subject to any regulation,” Lam said.

A spokesman for the Consumer Council said it had received 202 complaints related to medical beauty services in the first nine of the year. For all of 2022, only 220 complaints were received.

“The council is highly concerned about the potential risks involved with medical beauty services,” he said. “Should any issues arise during the treatment, it might pose long-term and irreparable physical and psychological damage.”