The dance cluster has mushroomed into Hong Kong's largest ever Covid-19 group with 132 cases, including 50 which came to light yesterday.
Authorities also revealed that a 61-year-old dancer sought medical attention 18 days after developing symptoms, during which she could have infected nine others who visited other dance floors.
Among 73 cases reported yesterday - a three month high - 10 were imported, 55 linked to previous infections and eight from unknown local sources.
More than 70 preliminary patients are awaiting confirmation.
Chuang Shuk-kwan, head of communicable disease from the Centre for Health Protection, said seven more premises have been involved in the cluster.
These are Kwan Ho Seafood Restaurant in Mei Foo, Hsin Kuang Banquet Hall in Sha Tin, Ging Bao Entertainment Production in Aberdeen, Sing Fai Hall in Kowloon Bay, Victor Yan Studio in Cheung Sha Wan and the World Dancer Performing Arts Federation and Starway Music Studio in Tsim Sha Tsui. Those who have visited them since November 1 will have to take a test.
The government has also commissioned private laboratories to set up seven mobile sample collection points in Tsuen Wan, Sai Kung and Tai Po, which began operation yesterday.
"Apart from dancers, a small portion of the cluster arose from second and third-generation transmissions," Chuang said.
"It also grew out of many dinner-dance events. If citizens have been to these kind of activities or any crowded places, please get tested as soon as possible."
The 61-year-old woman was found to have developed symptoms early but continued to dance in San Po Kong's Hsin Kuang Banquet Hall and Mong Kok's Kam Lai Sing before she went to the hospital.
Five others who had been to Hsin Kuang and four from Kam Lai Sing were subsequently infected.
Among the nine, two visited five other dance studios and spread the virus to seven others, meaning the 61-year-old could have led to 16 infections in total.
Two workers from Hsin Kuang and Kam Lai Sing were also infected.
On yesterday's new cases, Chuang said one of them worked at the X-ray department of Union Hospital in Tsuen Wan. A colleague tested preliminary positive.
Another is a dance teacher who coaches classes at True Light secondary school. A dozen students who attended her lessons are staying home until their test results are out.
Of the eight unknown-source patients, four were housewives from Wong Tai Sin, Tsuen Wan, Ho Man Tin and North Point and two were jobless men from Mong Kok.
Other unlinked patients were a woman who lives in Kennedy Town and works at Kwai Chung's Metroplaza and an engineer who lives in Ma On Shan and oversees construction sites in West Kowloon and Tai Kok Tsui.
Secretary for Food and Health Sophia Chan Siu-chee yesterday warned social distancing measures will be further tightened.
She added that the rapid surge and spread of patients across districts show there are a lot of hidden transmission chains in the community.
Government adviser David Hui Shu-cheong from Chinese University called on authorities to order dance premises to close.
He also urged the government to suspend classes, return to home office arrangements and tighten the cap for restaurant tables.