Australia has been an important contributor to a vaccine access organisation that has helped halve childhood morality.

A report from Gavi, the Vaccine Alliance, says it will have immunised one billion children by 2025, saving an estimated 17 million lives.

Gavi - a public-private partnership including governments, the World Health Organisation, UNICEF, the World Bank and the Bill and Melinda Gates Foundation - pools demand for vaccines in poorer countries and buys them at scale to boost access.

It supports child immunisation against human papillomavirus, diphtheria, tetanus, pertussis, hepatitis B, haemophilus influenza, pneumococcal and Japanese encephalitis.

Gavi also targets measles, rotavirus and polio, and holds stockpiles of cholera, yellow fever and Ebola vaccines for emergencies.

Brendan Crabb, from Pacific Friends of Global Health, said the milestone showed the value the program has delivered to Australian taxpayers, after the country pledged more than $600 million to global vaccine efforts in recent years.

"Gavi is a game-changer," Professor Crabb said.

"The increase in immunisation has helped halve childhood mortality."

He said investment in universal health-care access made both moral and economic sense.

"For every $1 spent on immunisation in Gavi-supported countries, $21 is saved in health-care costs, lost wages and lost productivity," Prof Crabb said.

Nossal Institute for Global Health's Helen Evans said the program was enormous value for money.

"It frees up the health services to get on with a lot more proactive preventive work, working with child and general health and with non-communicable diseases," Professor Evans told AAP.

"Millions of children are vaccinated by these life-saving vaccines that they wouldn't otherwise have had access to."

Prof Evans, a former deputy chief executive at Gavi, which is headquartered in Switzerland, said Australia's contributions to the project helped ensure its Indo-Pacific neighbours shared in vaccine programs.

"The Indo-Pacific region, our partner countries in the region, tend to fall a bit off the map to people sitting in Geneva,'' she said.

"That's partly because the burden of diseases in Africa is so big, this part of the world tends to get a bit forgotten.

"Having a seat at the table means you have a say about the needs of our region."

Prof Evans also noted the contribution Australian research has made to vaccines, with the human papillomavirus and the rotavirus vaccine having been developed in Australia.

She said sometimes it was hard to comprehend the reality of having a child sick with a preventable disease in a country with limited health resources.

"I've seen children, babies with pneumonia with their chest sucked in and there isn't any oxygen even in the health clinic or the hospital," Prof Evans said.

"It's a really, really important contribution that we can all make."