On this edition of Africa 54, a potential new malaria vaccine has proved highly effective in a trial in babies in Burkina Faso, showing a preliminary efficacy rate of 77 percent; Chad's ruling military council rejects an offer from northern rebels for a ceasefire and talks; The death toll in clashes this month between Ethiopia's two largest ethnic groups, the Oromo and Amhara, in the northern Amhara region may be as high as 200.