b) The emergence of new cases of polio linked to the oral vaccine had been reported in (20) a number of African and Asian countries, revealing that there are now more children being paralyzed by viruses originating in vaccines than in the wild. Viral contamination of a biological may arise from many factors, from handling to the origin of the materials used in the cell culture. i) What could be the reason for the outbreak in those countries? ii) The method of producing attenuated "live" vaccines involve passing the disease- causing virus through a series of cell cultures or animal embryos (typically chick embryos). Explain the procedure in details and cite the reason why the method involve passing a virus through a non-human host? a