More than 100 people are already in isolation after Victoria’s second hotel quarantine leak of the coronavirus in less than a week.

The woman, who works as an authorised officer at the Holiday Inn at Melbourne Airport, tested positive on Sunday after she completed a shift.

Her positive test was revealed in a flurry of late-night virus alerts from Victorian officials.

She had previously tested negative after a shift on February 4.

In Victoria authorised officers issue paperwork to hotel arrivals and help with transfers of people to other hotels if they are diagnosed with the virus. They don’t work on the same floors as guests.

On Monday, Victorian Police Minister Minister Lisa Neville said genomic testing would be used to work out how the worker caught the coronavirus.

“There doesn’t appear to be any breaches of infection prevention control procedures that are shown in [her] engagement with anyone who was entered or exited the hotel at any point,” she said.

Authorities are still interviewing the infected worker, and have boosted testing across Melbourne’s north-west as they try to stamp out the quarantine leak.

Tweet from @VicGovDH

It came just days after a security guard at an Australian Open quarantine hotel in Melbourne’s CBD was also confirmed to have the virus. There have so far been no further infections associated with his case.

Victorian testing commander Jeroen Weimar said 15 close contacts in the latest case had been identified, as well as up to 90 workplace close contacts. They include several police officers and Australian Defence Force personnel.

Authorities have released a preliminary list of exposure sites, but are still interviewing the hotel worker. The list is likely to be updated throughout Monday.

Initial exposure sites:

Visitors to the following venues at the specified times must immediately get tested and isolate for 14 days:

• Marciano’s Cakes, Maidstone, February 5, 9.45-10.25am
• Dan Murphy’s, Sunshine, February 5, 5.50-6.30pm
• Off Ya Tree Watergardens, Taylors Lakes, February 6, 1.17-1.52pm
• Dan Murphy’s, Sunshine, February 6, 6.50-7.30pm
• See the latest Victorian exposure sites here

Ms Neville said authorities were continuing to review Victoria’s hotel quarantine after the two recent breakouts. Air-conditioning is one focus of the review.

“We’re still pretty confident about the engineering reports that show that there’s no sharing of air between rooms or into common areas,” Ms Neville said.

“But again, we’ve got an occupational physician who’s coming in with the engineering team to have a look to see if there’s anything else with air-conditioning or any risk there.”

Meal and other deliveries to individual rooms are now staggered, while hotel staff must wear face shields as well as surgical masks.

“We’ll also start today the testing of staff on their days off,” Ms Neville said.

“All these changes are about continuing to make the necessary adjustments to the program as new evidence comes to light, as we see different sorts of transmission occurring in our program.

“Our key aim here is to not just have a robust hotel quarantine program, but a robust outbreak management team and contact-tracing system.”

Tweet from @NSWHealth

NSW alert for ‘low-level’ case

NSW is investigating the source of a coronavirus infection in a returned traveller, who tested positive after their 14-day quarantine.

NSW Health confirmed another day without local infections on Monday, as inquiries into the traveller’s case continued.

It has started a “precautionary public health follow-up” to the latest case, including alerts for several venues visited by the returned traveller last week. They include an Officeworks at Fairy Meadow, north of Wollongong, a cafe at Brighton Le Sands in Sydney’s south and other shops, a hotel and a beach in Wollongong and the Illawarra.

The traveller tested positive on the 16th day after arriving home, having returned two negative tests during their 14-day quarantine period.

“The person did not have any symptoms but underwent testing as part of the recently enhanced day-16 follow-up,” NSW Health said on Monday.

“Test results indicate that the person has a low level of infection and their household contacts have returned negative results to date.”

• See the latest NSW venue updates here

State health authorities think the infection was likely acquired overseas.

“There is no indication at this stage that there was transmission in the hotel quarantine setting,” NSW Health said.

Close contacts of the case are in self-isolation and are not associated with the venues of concern, NSW Health said.

Coronavirus testing sites in the region have also been boosted.

-with AAP