Cambodia's largest-ever immunisation program will launch today with the introduction of a new vaccine against rubella and measles, World Health Organization officials said yesterday.

The Ministry of Health aims to inoculate more than four million children between the ages of nine months and 15 years before December 31 through the $8 million project.

“This is the first time there’s been an immunisation available against rubella in the country,” said WHO technical officer Richard Duncan.“There’s still a lot of rubella transmission in Cambodia. It mainly affects unborn fetuses and the children are born with very severe side effects … but it’s a completely preventable disease.”

Previously, a measles vaccine was delivered to infants in two doses, one at nine months and one at 18 months. Health officials say the new vaccine will inoculate against both viruses at once.

“Cambodia’s immunisation program has a very successful reputation,” said Duncan. “In the two-year period following the [2011] vaccine campaign there were no cases of measles.”

According to the WHO, approximately 250 Cambodian children every year are born with severe side effects from in utero rubella infection.