The ACT, which remains in a one-week lockdown, has recorded two new virus cases, bringing total infections to nine.
One, a man in his 20s, has no obvious links to other cases and is being investigated, while the other is linked to an already announced exposure site, the Fiction Nightclub, in Canberra.
Additional exposure sites across the territory have been listed.
Chief Minister Andrew Barr said a record 5943 COVID-19 tests were undertaken across the ACT on Saturday.
"This really, really high level of testing is such an important surveillance tool for the ACT," Mr Barr told reporters on Sunday..
He welcomed the decision by the NSW government to lockdown the entire state from Saturday.
"That gives us an extra layer of protection," Mr Barr said.
"Whether you are on the ACT or NSW side of the border in the Canberra region everyone is in the same situation now."
He said the best thing for everyone to do is stay at home.
"We are aware of the challenges the cross-border situation presents and we're working with our NSW counterparts to make it as straightforward as possible," he said.
"The simple message, unless you absolutely have to travel, unless you absolutely need to leave home, don't...right at the moment."
He also noted that Prime Minister Scott Morrison had announced an additional one million Pfizer vaccine doses had been secured.
It will mean an additional 14,000 doses for the ACT.
"We anticipate that they will be available to us later in the week," he said.
"It is a welcome boost to supply."
But to put it into perspective, he said it is roughly the equivalent of one week's worth of doses that are being undertaken by ACT government clinics.
"It will allow us to do more but it isn't such a dramatic increase in supply that will allow us to do radically more," he said.
