PFIZER and BioNTech have struck a deal for South Africa's Biovac Institute to help manufacture around 100 million doses a year of their COVID-19 vaccine for the African Union, the firms said on Wednesday. The deal is to "fill and finish" the vaccine, the final stages of manufacturing where the product is processed and put into vials. It does not cover the complicated processes of mRNA drug substance production, which Pfizer and BioNTech will do at their own facilities in Europe. The agreement comes as Pfizer and BioNTech try to sway World Trade Organization (WTO) members from supporting a waiver…