Communities on Queensland's southern border have been put on notice that exemptions allowing them to cross over will end if coronavirus spreads north from NSW.
The warning comes two days after the Sunshine State closed its border with NSW and authorities on Monday relaxed restrictions blocking visitors from aged care homes.
"The border is difficult," Chief Health Officer Jeannette Young told reporters.
Dr Young said it was likely COVID-19 would spread through NSW north to the border communities and could cross over into Queensland.
"So it is really important that all those people along our border, whether they are in Queensland or NSW, think what is the next step if we have to close the border to everyone," she said.
Despite the potential threat, the state's aged care homes have been permitted to reopen to visitors following two weeks of high alert for an outbreak linked to two teens who dodged quarantine.
Health officials are now confident the women did not spread COVID-19 after returning from Melbourne in July and moving around the community for a week.
"Today was the very important day," Premier Annastacia Palaszczuk said, referring to the end of the two-week period since police placed the women in isolation.
"Aged care restrictions will be lifted, which I know means a lot to the families, especially over the last week or so when they have not been able to see their loved ones."
One new case of the virus was diagnosed overnight, a man in mandatory hotel quarantine who recently returned from overseas.
It brings the state's total to 1,089 COVID-19 cases, with 11 of those active.
"That is really good news, no community transmission in Queensland," Dr Young said.
"We can safely reopen our aged care facilities to visitors."
However, Bolton Clarke aged care facility in Brisbane's southwest will need to remain closed for another day and a half.
"Until we have confirmation that potential outbreak is over," Dr Young said.
Meanwhile, Queenslanders have been urged to remain cautious and continue following COVID-19 health restrictions.
"There are some reports in NSW of untraceable community transmission. That is of deep concern to us and we'll be monitoring it very closely," she said.
She also cautioned the organisers of a protest on the Story Bridge that was postponed for a week after Attorney-General Yvette D'Ath blocked it in court.
"There is a big community risk if people gather in large numbers," she said.
"In a pandemic ...it is very hard for this to go ahead."