South Africa’s Health Minister Dr Zweli Mkhize says new research estimates 12 million people – about 20% of the country’s population – could already have been infected with Coronavirus. This, the BBC reports, is much higher than the official cumulative number of detected Covid-19 cases which is 650,749. The research is based on examining seroprevalence – the amount of antibodies present in a patient’s bloodstream. In a statement released on Monday night, Mkhize said a decline in cases has raised questions of what level of immunity might exist in the country. Vaccinologist and member of the Ministerial Advisory Committee, Professor Shabir Madhi estimates between 35% and 40% of South Africans in densely populated areas could already have been infected, pushing the possible number of infections as high as 20 million.