There's a new intitiative to increase immunisation coverage in all provinces of Papua New Guinea.
Dr Inoch Posanai, the director for health improvement says it has been difficult to access remote areas so this has been a factor in the country's low immunisation coverage.
He says a severe outbreak of measles three years ago affected many who had not been immunised.
Dr Posanai says their aim now is to immunise the under fives to high school children who had missed out on their shots, particularly in rural areas.
"The health workers have to travel long distance, it require a lot of fuel, and if there's no road and they have to walk days and so forth. So those are some logistical problem affecting the delivery of services, and that includes immunising our children in those rural communities and that's why our coverage over the years has been very low."
Dr Posanai says so far they've completed immunising children in several provinces, including East New Britain, New Ireland and Morobe.