Barryt...Others have given you the answers. Namely, the virus only kills 1 or 2% of the people that it infects, and those people are mostly older than 60. So even if everyone in Africa was already infected, you would see at most a 0.5% increase in deaths given the age demographics.
Also, kindly note that some African countries are simply not able to provide accurate case counts for all of the social, economic and cultural reasons that have already been mentioned. And then there’s the political angle...Tanzania for example simply stopped reporting cases back in May.