TIM COCKS SOUTH Africa will vaccinate 40 million people, or two-thirds of its population, against COVID-19 in order to achieve herd immunity, its health minister has said, as a mutant variant drove daily new cases above 21,000 for the first time. He spoke as the government said it would receive 1.5 million doses of AstraZeneca's shot from the Serum Institute of India (SII), spread over January and February. Health workers have voiced concern that authorities have not acted fast enough to secure enough vaccines. A more contagious coronavirus variant, first found on South Africa's east coast late last year, is…