Mother-to-child HIV-2 transmission: comparison with HIV-1 and evaluation of factors influencing the rate of transmission. A systematic review.

A review and collection of data on HIV-2 mother-to-child transmission (MTCT) is absent in the literature. This systematic review and meta-analysis aims to provide a pooled estimate of the rate of HIV-2 MTCT and to identify factors influencing the rate of transmission. PubMed and EMBASE were used to identify eligible publications using a sensitive search strategy. All publications until February 2021 were considered; 146 full-text articles were assessed. Observational studies describing the rate of HIV-2 MTCT in a defined HIV-2 infected study population were included. Other publication types and studies describing HIV-1 or dually infected populations were excluded. Nine studies consisting of 901 mother-child pairs in West Africa, France and Portugal were included in the meta-analysis. The pooled rate estimate of HIV-2 MTCT for antiretroviral therapy-naïve women was 0.2% (95% CI 0.03 to 1.47%), considerably lower than that for HIV-1. The levels of maternal HIV RNA and CD4 cell count were positively related to the vertical transmission rate. Maternal HIV-2 infection did not significantly affect perinatal mortality. It was concluded that the vertical transmission of HIV-2 is lower than that of HIV-1. Maternal viral load and CD4 cell count appear to influence the rate of HIV-2 MTCT.