Early HIV infection in an individual is characterised by the rapid viral replication and diversification alongside a powerful immune response that results in the destruction of immune cells. The viral load in the blood of the infected individual has its peak during this exponential growth phase of the virus. Furthermore, the newly infected individual is also likely to continue the same risky behaviors that lead to their infection. Consequently, the risk of transmitting HIV to an uninfected individual is also at the highest during this period. It is observed in diverse HIV epidemics with different affected populations – heterosexuals, men who have sex with men, and injection drug users – that early HIV infection is responsible for up to 50% of new cases of infection. TASP (HIV treatment as prevention) is aimed at providing antiretroviral therapy (ART) to HIV-infected individuals, reducing their blood viral load to near or undetectable levels, thus preventing the transmission of HIV to an uninfected person.
Unfortunately, a major obstacle of TASP implementation is the high risk of HIV transmission from recently infected individuals who do not know that they are infected. The early stage of HIV infection is marked by nonspecific symptoms such as a rash, flu-like symptoms, or general feelings of malaise. Social network-based interventions such as Transmission Reduction Intervention Project and Project Protect aim to educate about early HIV infection and locate those recently infected to get them in care with the goal of preventing onward transmission of HIV.
Mathematical modelling performed by Eaton and Hallett (2014) on data from the South African HIV epidemic led to the conclusion by the authors that ART given to early HIV-infected individuals does not significantly change the HIV prevalence in the long term.
In a recent PNAS letter, Tanya, Gkikas, and Sam, our colleague from the Institute of Infectious Disease Research argue that Eaton and Hallett’s results might be biased by the data used, taken from the South African HIV epidemic where the incidence of HIV infection has been on the decline in recent years. While their findings are true to those settings, they might not be relevant to the new HIV epidemics at the exponential stage of growth or those well-established HIV epidemics that experience a breakthrough into other population groups (such as HIV epidemics in Latvia, Ukraine, and Greece).