Primary HIV-1 infection in users of pre-exposure prophylaxis

Pre-exposure prophylaxis (PrEP) has proven to be a highly effective and safe way to prevent HIV infection. Seroconversion and primary HIV infection are exceptional if adherence to PrEP is good. However, primary HIV infection while using PrEP can occur, albeit rarely, and HIV drug resistance might develop. Furthermore, the scope of PrEP is expected to expand, and clinicians might face potential seroconversions and primary HIV infection in patients starting or taking PrEP. The characteristics of primary HIV infection in users of PrEP are poorly described. PrEP users present a lower viral load peak during primary HIV infection and, frequently, fewer symptoms than individuals not exposed to PrEP. Additionally, PrEP prolongs the stages of seroconversion, thus potentially complicating diagnosis of primary HIV infection. Drug resistance is rare, occurring mostly when PrEP is initiated in undiagnosed patients who are at an extremely early stage of infection, in whom detection of HIV-RNA was not used to rule out HIV infection. Therefore, careful exclusion of primary HIV infection before starting PrEP is crucial. In patients presenting with primary HIV infection while on PrEP, a drug with a high genetic barrier (or even two) should be added to tenofovir disoproxil fumarate?emtricitabine until test results for resistance are available. HIV infection remains a public health problem, with 37?9 million people living with the virus by the end of 2018.1 With 1?7 million new infections every year, it is necessary to develop and establish new strategies to control spread of HIV. Preventive methods, such as antiretroviral treatment as prevention,2 educational interventions and condom use,3 male circum cision,4,5 and sterile needles6 have proven to be effective but insufficient. One of the most effective preventive tools is pre-exposure prophylaxis (PrEP), which consists of the administration of antiretroviral drugs before exposure occurs. Antiretroviral drugs are classified into several families, including nucleoside or nucleotide reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, protease inhibitors, and integrase-strand transfer inhibitors. Antiretroviral therapy (ART) regimens usually combine two nucleoside or nucleotide reverse tran scriptase inhibitors with a third drug. The coformulation of tenofovir disoproxil fumarate and emtricitabine, two nucleoside or nucleotide reverse transcriptase inhibitors, has proven