Fully vaccinated people who had travelled to high-risk regions in NSW and Victoria had to follow stay-at-home orders upon return to the ACT as they only had their second dose less than 14 days ago.

But the 14-day wait rule, which had not been explicitly stated in public communications, was only officially added to a public health direction on Wednesday afternoon, after people had been told to follow stay-at-home orders.

ACT Health has blamed the confusion on a drafting error in the public health direction.

The opposition has slammed the changed public health direction, saying the government had tried to hide this with retrospective rules.

The new direction came into effect at 2pm on Wednesday, after ACT chief health officer Kerryn Coleman defended the government's communication of the issue.

Dr Coleman told reporters on Wednesday morning the ACT government had always made clear it did not consider people effectively protected until two weeks after their second vaccine dose.

But the rule was never mentioned in relation to travel or other health restrictions.

Opposition health spokeswoman Giulia Jones said the change meant Canberrans were unwillingly forced to follow stay-at-home orders.

"Perfectly reasonable Canberrans who have checked the rules are having the rules changed under their feet," she said.

"Travellers have been give exemption forms that say there is a two-week wait-time before they can travel, but until yesterday, the chief health officer's public health direction said they had to wait only one week.

"How hard is it to make the form match up to what the actual rules are?"

The ACT government has identified a number of regions in NSW and Victoria, including large parts of Greater Melbourne and Newcastle, where there has been significant COVID-19 transmission.

Under the rules, fully vaccinated people are able to travel between high-risk areas and the ACT for any reason provided they fill out an exemption form.

The rules for high-risk geographical areas were outlined last week, before the territory opened up free travel between all of NSW and Victoria on Monday.

The public health direction governing this was brought into effect on November 1.

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That public health direction said a person was considered fully vaccinated if they received their second COVID-19 vaccine dose no later than seven days before entry to the ACT.

However, the direction was repealed on Wednesday and an updated direction stated a person was fully vaccinated no later than 14 days before entering the ACT.

An ACT health spokeswoman said there was an error in the first public health direction but that the rule had not changed.

"[The changes] included amending the definition of fully vaccinated to reflect the intended policy approach, amending the definition of a medical contraction certificate, as well as correcting some terminologies and typographical errors," she said.

The spokeswoman said only seven people were caught up in the chaos. She said they were working with those affected around possible changes to their quarantine requirements.

Health Minister Rachel Stephen-Smith conceded information could have been clearer.

"I think we could have been better at clearly identifying that that was the requirement," she told ABC radio.

"I think we should have been clearer upfront around what fully vaccinated meant for the purposes of travel but that information is now very clear on the website."

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