Effects of the transmission parameters on viral levels. The plots gives natural log of the viral levels against time. a gives the plots for viral levels when β1 and β2 are varied simultaneously, b gives the plots for viral levels when β2 is varied and c gives the plots for viral levels when β1 is varied. The viral level increases with increases in β1 and β2, however, increasing β2 had a greater impact on viral levels when compared to increases β1. The viral levels are more sensitive to β2 than β1.