UN officials also say it is likely the pandemic will kill at least 300,000 people in Africa and push nearly 30 million into poverty.
The past week in Africa has seen a sharp rise in coronavirus cases.
There have been almost 1,000 deaths and almost 19,000 infections across Africa, so far much lower rates than in parts of Europe and the US.
The UN Economic Commission for Africa – which warned 300,000 could die – called for a $100bn (£80bn) safety net for the continent, including halting external debt payments.
The WHO says the virus appears to be spreading away from African capitals.
It has also highlighted that the continent lacks ventilators to deal with a pandemic.
More than a third of Africa’s population lacks access to adequate water supplies and nearly 60% of urban dwellers live in overcrowded slums – conditions where the virus could thrive.