Unified Security Group state manager Mo Nagi said the guards were instructed by Department of Justice, Precincts and Regions staff to escort the couple to the hotel lobby.

"They advised us, then, that those two guests shouldn't have left and were COVID-positive," Mr Nagi told Victoria's hotel quarantine inquiry on Thursday.

The guards self-isolated after the incident.

His evidence came after MSS Security's general manager Jamie Adams told the inquiry he didn't know guests had COVID-19 until his subcontractors tested positive to the virus.

Mr Adams said he was assured by the Department of Jobs, Precincts and Regions that guests with symptoms would not be brought to quarantine hotels.

If a guest was to test positive, he was told medical staff would "escort that person out of the facility to another health facility".

"Those two factors in my mind significantly reduced the risk to our staff working at those hotels, given that the inference was that we wouldn't have any direct or indirect contact with COVID-positive guests," Mr Adams said.

He only learnt positive guests were staying at the hotels after eight security guards from two firms subcontracted by MSS Security contracted the virus at the Stamford Plaza in mid-June.

About 99 per cent of the state's second wave cases can be traced back to outbreaks at the Rydges on Swanston and Stamford Plaza hotels.

Sam Krekelis, also from MSS Security, said procedures didn't change at the hotel following the outbreak.

"We pushed again hard on the social distancing and the hand hygiene ... but nothing official, no," he said.

Mr Krikelis said the role of guards changed about two weeks into the program when they began escorting guests outside for smoke breaks and fresh air walks.

"Towards the end of our stay at the Stamford, we were asked if we could help deliver meals, breakfast, lunches and dinners," Mr Krikelis said.

In another incident, Unified Security's Mr Nagi was forced to restrain a female guest who escaped from her room, chased a nurse down the corridor and began to attack her.

"Police were on-site, but they were going to the end of the hallway to put full PPE on," he said, although "once they heard the screaming they were running".

The woman was taken to hospital before she was returned to the hotel six hours later.

Unified Security provided security to 13 Victorian quarantine hotels hosting returned overseas travellers, despite not being on the government's approved contractor list.

The majority of their guards were subcontracted from other companies, including six who tested positive to COVID-19 at the Rydges on Swanston in May.

Unified Security's national operations manager Nigel Coppick told the inquiry he didn't know why the company was offered substantially more work than MSS Security and Wilson Security.

"I was contacted and I was asked if we could support ... if we could provide the service safely, then we would," he said.

Mr Nagi said United Security guards were also tasked with delivering food, as well as "collecting linen and going into the rooms unblocking toilets".

"Once I was notified of that, I said we will assist in certain areas where we will not engage with the guests whatsoever," he said.

Mr Nagi was later asked to find staff to go to a toy shop to buy gifts for children in quarantine.

"I was happy to assist," he said.

The staff used a van filled with PPE to drop off the presents at different hotels.

The inquiry, headed by retired judge Jennifer Coate, continues on Friday.

Australian Associated Press