South Africa has signed an agreement to buy 20 million doses of the Pfizer-BioNTech dual-shot Covid-19 vaccine. A senior government official says the deal is a boost for the country worst hit by Covid-19 infections in Africa. It also adds to 31 million doses of Johnson & Johnson’s single-shot vaccine that the government has already secured. The first batch from Pfizer is expected to arrive later this month. The deputy director-general at the Health Department, Anban Pillay told Reuters he’s not allowed to disclose the price.