The potential liabilities are gigantic, and the risk calculation may put the equation under water.
It's the problem with a lot of medical products, particularly vaccines which are hard for pharma companies to market.
But it's made worse in regimes that are either litigious, have little in the way of caps over civil claims, or have Justice Systems which are compromised.
South Africa is a very corrupt state, it's just too easy for that system to act in a way that does not have integrity.
That's the real world risk/reward equation and it's unavoidable.
It's for similar reasons that it's a lot harder to raise financing for building infrastructure in SA (or anything else) than otherwise - the interest rates charged are considerably more as there's greater risk of failure, or problems, and even addressing commercial concerns becomes difficult if the justice system is compromised. For this reason, the loans to SA would have those risks 'priced in' at much higher interest rates ... which by the way is the other way pharma companies would normally give on the indemnity issue negotiation - by raising prices, but price becomes a problem for other ethical reasons.