On April 9, Deputy Public Health Commander Finn Romanes wrote to senior Department of Health and Human Services staff on behalf of Professor Sutton and his deputy Annaliese van Diemen.

The email, shown to Victoria's hotel quarantine inquiry on Wednesday, describes the program as lacking "a unified plan".

"There is considerable concern that the lead roles have not had an opportunity to be satisfied there is a policy and set of processes to manage the healthcare and welfare of detainees, for whom this program is accountable," Dr Romanes wrote.

"There are now considerable complexity and considerable risk that unless governance and plans issues are addressed there will be a risk to the health and safety of detainees."

Dr Romanes said Prof Sutton and Dr van Diemen wanted an urgent review into the structure of the program, which had only been operating for two weeks.

Prof Sutton told the inquiry Dr Romanes spoke to him before he sent the email.

"I did support this as being called out as something that required urgent review," he said.

"Dr Romanes was acting on behalf of me in highlighting concerns that he had."

The inquiry heard Prof Sutton did not agree with a decision to jointly appoint DHHS bureaucrats Jason Helps and Andrea Spiteri state controller during the pandemic

Under the state's plan for an influenza pandemic, the chief health officer is supposed to assume the role of a state controller and the "overall responsibility for emergency response operations".

It was decided Prof Sutton was too busy to assume the role.

DHHS secretary Kym Peake eventually stepped into the role in late July, which Prof Sutton said was appropriate.

Prof Sutton and his team were not directly involved in the operational planning or running of the state's hotel quarantine program.

He said he did not know security guards had been hired to oversee returned travellers until there were outbreaks at the Rydges on Swanston and Stamford Plaza hotels.

The inquiry also heard that a returned traveller was released from the Stamford Plaza while infected with COVID-19 and passed it on to the person who drove them home.

The returned traveller was unaware they had the virus.

At the time, COVID-19 testing was voluntary and available only to returned travellers with symptoms.

Those who did test positive to the virus, meanwhile, could not be held in hotel quarantine longer than 14 days and were told to continue to self-isolate at home.

Prof Sutton concedes there could have been other returned travellers who left quarantine unaware they had the virus.

In late June, it was revealed about 30 per cent of returned travellers in hotel quarantine had refused testing.

New laws were introduced on July 1, which forced returned travellers to spend an extra 10 days in hotel quarantine if they refused a COVID-19 test on their 11th day.

Mr Helps and Ms Spitieri will give evidence to the inquiry on Wednesday, as will Deputy Chief Health Officer Annaliese van Diemen.

Australian Associated Press