Advocates have criticised the government for not immediately alerting the sector after a cluster of cases involving disability care residents and support workers emerged last week.

The outbreak has also prompted renewed attacks on the federal government over its vaccine rollout for Australians with a disability.

More than a quarter of NDIS participants who live in group homes in Canberra are yet to receive a single dose, six months after the rollout started for the priority cohort.

The cluster has grown to 15 cases after an eighth support worker tested positive to the virus.

The outbreak had affected at least five service providers and sparked concern throughout the ACT's disability community, which have long-feared the prospect of the virus spreading to the vulnerable population.

Sharing Places in Pearce, which runs programs for people with an intellectual disability, was on Monday listed as a casual contact exposure site from 8.45am to 9.30am on August 11.

Rumours about the positive cases began to circulate last week.

The ACT's Office for Disability and ACT Minister for Disability Emma Davidson confirmed the outbreak to sector stakeholders in an email on Friday night, but it wasn't revealed to the wider public until Chief Minister Andrew Barr provided his daily update on Sunday morning.

Disability advocate Craig Wallace said if the government was able to alert the public in "real time" to outbreaks in aged care, it should do the same for new cases in disability care.

"I have a problem with that [lack of communication] ... we need to be maintaining trust, openness and transparency," he said.

Mr Wallace, who is head of policy at the ACT Council of Social Service, understood the need to maintain privacy and not "expose or vilify" individuals who contracted coronavirus.

But he said people with a disability had the right to know when cases were detected in the community.

Health Minister Rachel Stephen-Smith said she would take the criticism on board, but strongly defended the handling of the situation.

Ms Stephen-Smith said in any outbreak health authorities aimed to communicate with those directly involved before publicising the cases.

She said that process was more difficult in disability care, as it could involve contacting multiple providers, residents and workers.

Ms Stephen-Smith said there would have been "no public health benefit" in alerting the wider disability sector earlier as authorities had been working closely with those directly involved.

She indicated that it wasn't until Friday night that authorities were comfortable that all of the relevant people connected to the cluster had been contacted.

The email which Ms Davidson sent to the sector at 8.12pm, which The Canberra Times has seen, confirmed that was the case. The email confirmed there had been infections linked to the ACT disability sector, but did not say how many.

"It is absolutely a judgment call [not to immediately alert the sector or public], but it is absolutely not about hiding information from the community," Ms Stephen-Smith said on Monday.

"It is about making sure that those people who are directly affected get the information communicated to them, individually, directly ... that they have the supports in place before they hear it through the media."

The outbreak has prompted fresh outrage at the federal government, who are responsible for vaccinating residents and workers in disability care homes.

Just under 75 per cent of people in disability group homes had received one dose as of August 20, according to Commonwealth figures referenced by Ms Stephen-Smith.

About 54.5 per cent of NDIS participants in the capital have received their first dose.

Just over 54 per cent of support workers have had one dose, according to the figures.

Canberra-based disability group Advocacy for Inclusion believed an outbreak was inevitable because of the vaccination schedule.

It described the steps to prioritise and support people with a disability as "wholly inadequate".

"Our thoughts are with everyone affected; the people with disability experiencing Covid, those living in fear of the risk of Covid, families, and supports," the organisation's chief executive Nicolas Lawler said.

Mr Wallace said the federal government and the National Disability Insurance Agency had "utterly failed".

He called for immediate improvements to the rollout, including making it more accessible for people to access a vaccine, as well as weekly updates on its progress

He suggested rapid antigen testing could be introduced for support workers.

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