The results of the study, known as PROMISE, were presented at the International AIDS Conference (AIDS 2018), held last summer in Amsterdam. A large international study on the effectiveness of antiretroviral treatment to prevent vertical transmission (mother-child) of HIV has found two possible cases of HIV transmission when the woman was in a state of virological suppression, with several viral load tests whose The result was undetectable during the period during which the transmission took place. These results cast doubt on the concept that “undetectable is equal to intransmissible” in terms of breastfeeding.
An international team of researchers suggested studying whether or not it was possible for a mother with HIV and undetectable viral load to transmit HIV to her child during breastfeeding, given the uncertainty and lack of conclusive studies in this regard. The PROMISE study was carried out in 14 countries and had the participation of women with CD4 levels greater than 350 cells / mm3, who were included in the study at three possible times: before giving birth, during the lactation period and after interrupting breastfeeding. The viral load of the mother was measured at the time of inclusion and at weeks 6, 14, 26 and 50 after delivery. Samples of newborns were taken at the time of inclusion, at 6 weeks and after that every four weeks to detect a possible HIV infection by viral load.
Seven babies from the maternal antiretroviral treatment group and seven from the group with newborn prophylaxis were infected during the study. Two of them were diagnosed at a time when their mothers had recent or very recent tests with undetectable viral load results.
There are several possible explanations for some of these cases. One of them is that, despite having an undetectable viral load in the blood, HIV can still be present in breast milk through blood cells that pass into the milk and may be infected by HIV. Given the large volume of milk consumed by the infant throughout the breastfeeding phase, this risk of transmission could eventually be higher than previously believed. Another possibility would be the transmission of the baby at some point of lactation where the mother went from having the undetectable charge to detectable, and returning again to be undetectable
In any case, these results still generate more uncertainty in the context of breastfeeding of women with HIV. What does seem clear is that it is increasingly difficult to defend that “undetectable is equal to intransmissible” is a message applicable to the field of breastfeeding.