Unless you can explain it and convince the blacks in Africa it’s probably going to be too late.
The rumor mill has taken over.
In the minds of black Africans there is a cure and the whites are withholding it.
They have set up a wholesale slaughter of whites in Africa by announcing the possibility of a cure then withholding it.
The adaptive immune system typically takes 2 weeks to mount a defense and build sufficient titer in the blood. I did that with rabbits in grad school. Multiple rabbits with multiple antigens. A weekly blood draw tracked the titer against the antigen. When the appropriate level was reached, the rabbit was sacrificed. The entire blood volume was withdrawn. About 120cc for an average lab rabbit. Erythrocytes allowed to settle and serum drawn off and saved. That description omits the process of purifying the antigen before the process starts. It's not a fast process. It takes a lot of critters to generate the serum. You have to raise the critters first.
As for "explaining", you are dealing with people in fear of their lives. Don't expect rational behavior. If they engage in wholesale slaughter of whites, then cut them off. No further assistance of any kind. It wouldn't be the first time. Zimbabwe comes to mind.