Theme 3 looks at the effects of demographic changes in China on HIV [29] and the spread of HIV among men who have sex with men [30] . Theme 4 examines in-host modeling -a crucial element in tackling the disease, often overlooked by epidemiologists -by proposing new methods for evaluating the efficacy of antiretroviral treatment [31] and examining antioxidant supplementation as HIV therapy, with a focus on injecting drug users [32] .