Coronavirus cases in Africa are rising so quickly that the continent will soon face its worst week since the start of the pandemic, with the more infectious delta variant of the disease becoming more widespread.

Almost 202,000 new cases of the illness were reported in the past week, and infections are doubling every three weeks, World Health Organization Regional Director for Africa Matshidiso Moeti said in an online briefing Thursday. More than 5.4 million cases have been reported on the continent, with 141,000 deaths, she said.

“The speed and scale of Africa’s third wave is like nothing we’ve seen before,” Moeti said. “The continent is on the verge of exceeding its worst week ever in this pandemic.”

Fourteen African nations are facing a resurgence of the virus, 12 of which have detected “variants of concern,” including nine with the delta strain, she said.

Africa is the world’s least-vaccinated continent. While the U.S. and U.K. have fully inoculated almost half their populations, that figure is just 1.1% for Africa, according to the Africa Centres for Disease Control & Prevention.

Meanwhile, the Democratic Republic of Congo is expected to take delivery of 5 million additional doses of two or three different vaccines in the next few days, according to Professor Jean-Jacques Muyembe, the managing director of the country’s National Institute for Biomedical Research.

It’s “part of our strategy so that the population can choose what vaccine it wants to take and help with vaccine hesitancy,” he said, while conceding it’s still not nearly enough. “The five million doses will not even suffice, not even for Kinshasa.”