Taking a quick look, it seems that South Africa went for the Pfizer-BioNTech and J&J vaccines. If vaccine supply was the issue, they should have bought Indian and Chinese vaccines. Those vaccines were actually the best bang for the buck for the global South at the time: their marginally lower efficacy was more than compensated for by their far better availability. It seems like the problem for SA, ironically, is that it stuck too close to the West and did not think independently enough.