Yellow fever outbreaks in Angola and the Democratic Republic of Congo are "under control" after a massive vaccination campaign involving millions, the World Health Organisation said Tuesday.

Yellow fever has been raging in Angola since December, with the number of suspected cases surging above 4,000.

"The risk of a major is now over," the head of WHO's pandemic and epidemics department, Sylvie Briand, told reporters in Geneva.

The UN health agency had raised alarm over the prospect of a significant outbreak in several countries after the viral haemorrhagic disease began raging in Angola.

Yellow fever subsequently spread into DR Congo, which saw more than 2,600 suspected cases.

Isolated cases were reported in China among people who had travelled to southern Africa.

According to WHO statistics, as of September 9, there have been 121 laboratory confirmed yellow fever deaths in Angola and 16 in DR Congo during the current outbreak.

WHO had been particularly concerned because were heavily concentrated in major urban centres like Luanda and the Congolese capital Kinshasa.

In an accelerated campaign, 7.7 million people were vaccinated in Kinshasa in less than two weeks.

Separately, 15 million people were immunised across Angola, more than 65 percent of the country's population.

Angola has not recorded a new yellow fever case since June 23, while the last new case in DR Congo was registered on July 12, Briand said.

She warned that vaccination against remains low across Africa and that there is still a risk of a large-scale outbreak in the future.

That risk has been compounded by increased urbanisation on the continent, since transmission rates are higher in more densely populated areas.