We estimated that 70% of all individuals diagnosed with HIV in Denmark were virally suppressed. The Center for Disease Control and Prevention has estimated that the corresponding proportion in the United States is only 35%. This difference is mainly due to lower rates of linkage to and retention in care. Each of the steps of the continuum of HIV care in the United States as well as possible effects of addressing gaps in care have been reviewed by Gardner et al. They found that incompletely engaged individuals account for the largest proportion of HIV infected individuals with detectable viremia and that multiple sequential barriers have to be overcome, since improvements in any single component of the continuum of care will have minimal impact on the proportion of HIV infected individuals with vireamia. In Denmark 95% were linked to care and 93% of those linked were retained in care, whereas the corresponding numbers 
for the United States were 77% and 66%. In the United States socially disadvantaged groups are disproportionally affected by HIV, which likely partly explains the difference. But dissimilarities in the organization of the health care systems may also be important. User’s fees and lack of health insurance may be barriers to engagement in care. However, differential methods for data collection and analyses may affect estimates. If nationwide data are not available or if it is not possible to link data from different registers at the individual level, the proportion of patients not retained in care may be overestimated due to migration. In spite of the marked increase in the proportion of HIV patients with viral suppression during the study period, no decrease in incidence of HIV diagnoses has been observed. On the contrary there has been a slight increase in the annual number of newly diagnosed MSM. This is discouraging given the hopes to the strategy of ��treatment as prevention�� fuelled by trials showing high efficacy of HAART in reduction of mother to child transmission and prevention of transmission in serodiscordant couples. It has been speculated that increases in unprotected sex counterbalance the effect of reductions in community viral load. An additional explanation might be that primary HIV infection drives a considerable part of HIV transmission or that a large fraction of individuals living with HIV are undiagnosed. There are no well documented estimates of numbers of individuals living with undiagnosed HIV in Denmark and whether this number has changed during the study period is unknown. Generally there has been a slight increase in the median CD4 count at time of HIV diagnosis and a reduction in the proportion of patients with advanced disease at HIV diagnosis. Reviews of the evidence on strategies to curtail the HIV epidemic conclude that treatment as prevention is unlikely to eliminate HIV on its own and that a combination of interventions are needed to control the epidemic.