The development came as officials prepared to roll out the third stage of the vaccine pass scheme on Tuesday, where most residents will need three jabs to enter premises unless they already had their second dose or recovered from a Covid-19 infection less than six months ago.

Officials revealed on Monday that about 10 per cent of more than 100,000 premises had not updated their risk-exposure app, used to verify customers’ “Leave Home Safe” vaccine records upon entry. They will have to update it on Tuesday to admit customers for their business operations.

Anthea Cheung So-may, director of business group Lan Kwai Fong Association, maintained the industry had been complying with regulations, but the government did not say whether disc jockeys fell under the category of live performances until after inquiries from the sector.

“When formulating the laws, the government did not explain every activity defined as live performances and dancing. But it was not specified in the requirements that they gave us earlier, so some operators said they had overlooked it,” Cheung said, urging the government to clarify the rules in detail.

“I hope we can balance between doing business and epidemic prevention. For example, the government can allow live music to be played as long as relevant staff members wear masks and keep their distance from customers.”

Health authorities on Saturday revealed that a cluster was found at the Zentral nightclub, which had grown by eight cases to 23 infections as of Monday. Another cluster with 22 cases was found in the Iron Fairies and J. Boroski bar in the same area, including 11 reported on Monday. All 31 environmental swabs taken from Iron Fairies have come back negative.

Patients from both clusters went to the premises between the night of May 21 and the early hours of May 22, when 700 visitors were logged on the government’s “Leave Home Safe” risk-exposure app at each nightclub.

Social-distancing rules currently allow bars, pubs and nightclubs to open until 1.59am, while live performances and dancing are banned.

Dr Albert Au Ka-wing, principal medical and health officer at the Centre for Health Protection, said investigations into the infections were still under way, but initial inspections showed “poor or inadequate” ventilation, and maskless guests dancing and drinking in a crowded, enclosed area.

When asked if disc jockeying at pubs was considered live performance, Au said the relevant authorities would look into whether regulations needed to be tightened or if rules had been broken.

Au also said all indicators including severe infections and hospitalisation figures showed the local health situation was at a stable level.

The Food and Environmental Hygiene Department said it was still investigating the clusters.

Ben Leung Lap-yan, charter president of the Licensed Bar and Club Association of Hong Kong, estimated there were 10 per cent of bars in Hong Kong that hired disc jockeys to play music.

“According to my knowledge, there were also police inspections on that night [when the cluster emerged], but no violations of the rules were found,” he said. “There might be video clips online that showed people dancing or some disc jockeys were not wearing masks when playing music, which the industry has to reflect on.”

But he said it was difficult to define whether the customers were dancing or not as most of the clubs did not have a dance floor.

“A lot of bars and clubs used to apply for a licence for dancing and designate an area for dancing in the past. But it is very rare now as the industry has replaced ‘discoing’ with ‘clubbing’,” he said. “[Unlike discoing], clubbing does not require a huge designated area for dancing. People mostly just dance next to their tables.”

Leung suggested that as long as the disc jockeys followed social-distancing rules, they could be seen as staff members who played music rather than performers, adding that lighting technicians in nightclubs were also not seen as such.

“There are a lot of grey areas,” he said. “I hope the industry is able to discuss with the authorities on how to improve, and they can also provide us with more guidelines. I hope that we do not have to suspend business again.”

New Hong Kong clusters spark calls for no further easing of Covid curbs in bars

Meanwhile, an outbreak in the Tai Koo area has continued to grow, with health authorities identifying four new patients suspected to be carrying the Omicron BA.2.12.1 subvariant.

A five-year-old girl, her mother and their domestic helper living in Mount Parker Lodge in Quarry Bay were found to be infected. They are in the same building as another infected family tied to an outbreak at a McDonald’s outlet in Tai Koo.

The other case is a 51-year-old man who lives at Kao Shan Terrace in Tai Koo Shing. The source of his infection is unknown.

The McDonald’s cluster in Tai Koo originated from a traveller suspected to have been infected while quarantining at a hotel in Sheung Wan but whose case was only detected when she was already back in the community. As of Sunday, there were at least 27 cases tied to the cluster.

“We have not found any direct epidemiological link between the four cases and other previously infected patients … But what they have in common is that they all live in that district,” Au said.

Hong Kong’s restaurants, bars ‘could lose up to 25 per cent of business this week’

“The McDonald’s restaurant which previously had an outbreak reported is also situated in that area. We believe that some silent carriers visited there and caused infections [to spread].”

Au urged residents in Tai Koo Shing to test themselves if they had shown any symptoms.

Separately, Chief Executive Carrie Lam Cheng Yuet-ngor on Monday published her last report on Hong Kong’s anti-epidemic efforts, noting that the fifth wave had “overwhelmed” the city’s capacity for tackling the health crisis.

She also thanked the central government for its assistance and residents for their cooperation.

In order to fulfil requirements for reopening the border with mainland China, the government had “steadfastly” adopted measures to avoid imported infections and prevent a rebound in local cases.