The head of the World Health Organisation in Papua New Guinea says the government is surprised by the progress in a mass vaccination programme to tackle polio, measles and rubella.
Luo Dapeng says since polio returned to the country last year, huge efforts have been made to vaccinate more than three million children under the age of 15.
26 children are confirmed to have had polio, and one child has died as a result.
That outbreak was linked to poor vaccination coverage nationwide.
Dr Luo said the current programme has traversed the country, combining the polio vaccine with measules, mumps and rubella immunisations to protect children.
Dr Luo said the WHO and the UN children's agency UNICEF have helped to train more 12,000 health workers and the results are impressive.
"The achievement, what the PNG government have actually achieved for the last few rounds has been a surprise to many of the partners, even the government themselves," he said.
"They realise they can do it if they get the proper resources and support from outside, the proper technical support like WHO and UNICEF, they can deliver on the service at a critical time like an emergency."
Luo Dapeng said the current phase of the vaccination programme aims to immunise more than a million children in three weeks.