Based on the estimated outcomes for each CD4 value in the normal range, we obtained that the median year of seroconversion was 1995 (Q1-Q3, 1991 to 2000), age at seroconversion was 31 (Q1-Q3, 25 to 39) years and duration of infection from seroconversion until HIV diagnosis was 6.9 (Q1-Q3, 3.9 to 10.1) years. Here, CD4 is linked to infection.