A large proportion of HIV transmissions occur during recent infection or antiretroviral treatment interruptions, Swiss investigators report in Clinical Infectious Diseases. Overall, 44% of transmissions were associated with recent infection and 14% could be attributed to treatment interruptions. The authors believe these findings represent a major challenge for treatment as prevention (TasP) strategies.
“Our findings imply that TasP needs to be accompanied by interventions to tackle treatment continuity, adherence, retention in care, and, importantly, early diagnosis,” comment the investigators.
Previous studies have shown that between 10% and 80% of HIV transmissions are attributable to patients who were recently infected with the virus. Knowing the proportion of early phase transmissions is important, especially given the recent emphasis on the use of HIV treatment as prevention.
Indeed, the impact of treatment as prevention on the ongoing epidemic could be limited if a high proportion of transmissions originate in individuals with recent infection. A high proportion of such patients are unaware of their status and are therefore unable to benefit from HIV therapy. Moreover, because recent infection is associated with a very high viral load, individuals with this phase of infection are often highly infectious.
Investigators from the Swiss HIV Cohort Study therefore conducted a retrospective analysed of the genetic characteristics of stored blood samples obtained from Swiss HIV patients. Using a technique called phylogenetic analysis, they looked for infections with similar genetic profiles which were likely to be part of a transmission cluster.