Health authorities in 112 countries will launch an unprecedented one week vaccination drive from Saturday in Europe, the Americas and Middle East, the UN's World Health Organisation said Friday.
It is the first time that such immunisation campaigns are being launched simultaneously across separate WHO regions, in an attempt to expand general vaccination coverage and raise awareness of the importance of vaccines.
The UN health agency said that some 2.1 million children in the Middle East did not receive a basic jab against diphteria, tetanus and whooping cough last year.
In the region "25 percent of deaths of children under five years old are due to diseases that could have been prevented by a vaccine," WHO spokesman Daniel Epstein told journalists.
"A great number of lives" could also be saved by new vaccines against pneumonia and rotavirus, which is behind many severe cases of diarrhoea, he added.
In the WHO's Europe region, which stretches through Russia, Turkey and parts of Central Asia, the campaign will focus on measles and rubella.
"In European countries, many of them, immunisation coverage is below the recommended 95 percent level and there have been ongoing measles outbreaks in some of these countries," said Epstein.
Declining measles immunisation rates in western Europe have been major cause for concern at the global health agency, jeopardising its target of eliminating the disease from the area this year.
Children in affluent countries are largely at risk of measles infection because of skepticism about immunisation or the belief that the disease is not serious because it was largely under control, according to the WHO.
Measles is a contagious respiratory illness characterised by high fever and the eruption of small red spots, and can lead to life-threatening complications in children.
In North and South America, regional immunisation drives are focusing on border areas of Nicaragua, Suriname, French Guyana, Haiti, the Dominican Republic, as well as in the United States and Mexico, slums and big cities.