As the fourth Covid wave approaches, Pfizer and BioNTech have applied to have their coronavirus vaccine approved by the South African Health Regulatory Products Authority for use as a booster. The vaccine is already the most widely used in South Africa and is set to become the first to be approved for use as a booster in the mass roll-out of vaccines across the country, where hesitancy remains a problem. The authority will assess the data to determine the safety and efficacy of its use as a third dose. Photograph: Bloomberg