Passengers on a Canberra bus that went from Dickson to Kaleen last week are being urged to self-isolate, amid concerns they may have come into contact with a confirmed case of COVID-19.

Key points: Thirty-nine people have now been diagnosed with COVID-19 in the ACT

Thirty-nine people have now been diagnosed with COVID-19 in the ACT Passengers on a bus caught by a confirmed case are being told to self-quarantine

Passengers on a bus caught by a confirmed case are being told to self-quarantine ACT public transport will only be for essential travel, though services remain for now

The person who caught the number 31 bus from Dickson to Kaleen at 3:50pm on March 17 was a previously confirmed case, but authorities on Tuesday urged anyone who was on that bus, which was scheduled for 3:33pm but ran late, to quarantine themselves.

Seven new cases were confirmed in the ACT on Tuesday — two men and five women, aged between 21 and 75.

There are now a total of 39 confirmed cases of COVID-19 in Canberra.

Three of those are in hospital in a stable condition.

Announcing the changes, the ACT Government said the normal public transport network would continue operating for the time being, but should only be used for essential travel.

"Don't use public transport to get on the beers at your mate's house, and definitely do not use public transport if you are feeling sick or unwell," Transport Minister Chris Steel said.

He said people who needed help getting to a testing facility should not take the bus or tram, but call 1800 022 222 to arrange alternative transport.

Who should get tested? COVID-19's main symptoms are fever (above 38C), cough, sore throat and shortness of breath. Seek medical help if you: recently travelled overseas or on a cruise ship, and developed symptoms within 14 days of returning to Australia

recently travelled overseas or on a cruise ship, and developed symptoms within 14 days of returning to Australia were contact with someone who has COVID-19 and you developed symptoms within 14 days of last contact

were contact with someone who has COVID-19 and you developed symptoms within 14 days of last contact are a healthcare or aged-care worker with recent onset of symptoms, irrespective of travel history

are a healthcare or aged-care worker with recent onset of symptoms, irrespective of travel history live in a high-risk setting (e.g. aged-care or other care facility, boarding school, operational military setting, detention centre) and have symptoms

live in a high-risk setting (e.g. aged-care or other care facility, boarding school, operational military setting, detention centre) and have symptoms have links to an area where COVID-19 outbreaks have occurred in Australia, and have symptoms If you wish to be tested, call your GP, visit the drive-through testing centre at EPIC or the Weston Creek walk-in centre, or call Healthdirect on 1800 022 222. See the ACT Health website for more information.

The Government has also introduced changes to buses, including banning the use of cash, only allowing entry and exit via rear bus doors, and keeping front bus seats clear, in order to minimise public contact with drivers.

Mr Steel said there had been a 21 per cent drop in public transport passenger numbers compared to the same week last year.

He said the Government would delay planned changes to the public transport network.

"Our focus must be on trying to maintain current transport services as much as possible," he said.

First 'pupil-free' school day, but childcare centres continue

From Tuesday Canberra schools are also being run "pupil free".

The mixed messaging confused parents, and raised questions over whether childcare centres would follow suit.

When asked, the ACT Government said it was up to individual childcare providers to determine whether they could safely operate.

Communities@Work chief executive Lee Maiden said the number of families withdrawing children so far has been small.

She said the organisation had reduced the notice period for parents to withdraw by a week, but children who pulled out would still lose their place at preschools.

"If we have families on the waiting list looking for a place we would certainly be offering it to the next person on the waiting list, so that we can continue to operate," Ms Maiden said.

She said centres were implementing extra precautions.

"We actually ask families as they come in to our services to make sure they use hand sanitisers, our equipment and toys are always washed regularly," she said.

"If we're told we would need to close we will close our services."