SOUTH Africa has signed an agreement to buy 20 million doses of the Pfizer-BioNTech dual-shot COVID-19 vaccine, a senior government official has announced, boosting plans to ramp up vaccinations from this month. The deal is a boost for the country worst hit by coronavirus infections in Africa, as it 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 in April, Anban Pillay, deputy director-general at the Department of Health, told Reuters. He said he was not allowed to disclose the price, but…