CD4 and HIV infectious disease: Using the described model, the estimated number of people living with undiagnosed HIV infection and with CD4 count < 350 cells/mm3 in Italy was 6,028 (95% CI: 5,090–7,826) in 2012, 6,156 (95% CI: 4,891–8,517) in 2013, and 5,899 (95% CI: 4,882–7,786) in 2014.