By Miranda Eeles
The biggest ever immunisation campaign for measles, mumps and rubella has been launched in Iran.
Measles cases in Iran are feared to be on the rise
Over the next three weeks the government is hoping to vaccinate 33 million people - around one-half of the Iranian population.
Iran has a good history of immunisation, but health experts are worried the number of measles cases could be on the rise.
President Mohammad Khatami hailed the drive at a launch ceremony on Saturday.
Measles is the biggest killer of children under five in the world. The campaign is part of a global challenge to eliminate the disease by 2005.
From today until the end of December, Iran's ministry of health is hoping to vaccinate 11 million people a week.
They have been preparing the campaign for six years and have mobilised a whole network of volunteers in order to reach the most remote areas.
Most of the vaccinations will take place in schools, health centres and clinics.
They will also be operating in military barracks where attitudes towards immunisation are more relaxed.
Many Iranians, especially between the ages of 15 and 25, have never had more than one dose of the measles injection.
Health officials are hoping this campaign will encourage people to return to routine vaccinations.
The United Nations' Children's Fund representative in Iran, Kari Egge, welcomed the campaign.
"It is a part of the elimination of measles campaign, a global campaign, but is also a boost for the primary healthcare system in Iran because this year we have [already] had between 10,000 and 15,000 cases of measles," she said.
"This is of course something we need to tackle so we do not have epidemics around the country."
Recent research shows that more than 95% of the population has been immunised against measles.
Experts are hoping this campaign will avoid the risk of epidemics in the future and boost their overall routine immunisation system.