A senior health official told AFP that an outbreak of measles has killed 166 people in Malawi since January. He also termed it the worst outbreak in a decade.
"Our records show this is the highest number of people to have died from the disease in the past 10 years," said Storn Kabuluzi, the government's director of preventive health.
He said 52,000 people had caught measles over the past six months in the nation of 13 million.
"We are targeting six million children aged six months to 15 years for the mass immunisation," he said.
Neighbouring Zambia is also experiencing its worst measles outbreak in years, with 88 killed over two months, mainly around the capital Lusaka.