As the Royal Commission into Institutional Responses to Child Sexual Abuse commences its final public hearing, chairman Justice Peter McClellan has urged child protection reform and proper redress for victims.

The $500 million inquiry is Australia's longest royal commission, starting in 2013 and due to finish with a final report to the federal government in December.

In his opening remarks to the hearing, Justice McClellan said governments and institutions needed to focus on redress and regulatory changes, "designed to ensure that so far as possible no child is abused in an institutional context in the future".

"Survivors have waited too long for an effective response to their suffering and the future protection of Australian children must be given the highest priority," he said.

Justice McClellan and five commissioners have heard the testimony of more than 6500 child sexual abuse survivors in private sessions, with another 2000 people still awaiting a meeting.

More than 1200 witnesses have appeared at the commission in 400 days of public hearings.

Data gleaned largely from private sessions found there were more than 4000 institutions where alleged abuse of children occurred.

Religious institutions were most frequently named, with 60 per cent of survivors in private sessions reporting child abuse in a religious organisation. Just over one-third of survivors reported abuse in a government-managed institution.

"It is remarkable that failures have occurred in so many institutions," Justice McClellan said.

"It is now apparent that many of the characteristics of failure within institutions are common."

An analysis of alleged perpetrators found members of the clergy were most commonly identified by those attending private sessions, followed by teachers and residential care workers. The majority of alleged perpetrators were adult males, accounting for 94 per cent of reported abusers.

Counsel assisting the commission Gail Furness SC told the inquiry the statistics are likely to represent a fraction of child sexual abuse survivors.

"It is very likely that there are very many people who have been sexually abused in institutional contexts in Australia as children who have not attended a private session," she said.

The commission heard 64 per cent of people who attended a private session were male. Almost half reported they were abused when aged between 10 and 14 years, while 28 per cent were aged between five and nine years when the abuse allegedly occurred.

"When a child is sexually abused, the effects can be devastating," Ms Furness said. "For some, the impacts of the abuse, and an institution's response to it, last for their whole lives."

The impact of abuse is widespread, the inquiry heard.

"Child sexual abuse affects the whole community," Ms Furness said.

"The effects ripple outwards, adversely affecting victims' parents, siblings, partners, carers and children."

The hearing into the nature, cause and impact of abuse continues.

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