A retrospective cohort study on protective efficacy of multidrug antiretroviral treatment in reduction of HIV transmission through the vertical route in West Bengal, India

Introduction
Human immunodeficiency virus (HIV) is transmitted vertically from an infected mother to her child. This is a potentially preventable route of HIV transmission and such transmission can be reduced significantly with appropriate prevention of parent-to-child transmission (PPTCT) measures. This study was aimed at determining the protective efficacy of a multidrug, PPTCT regimen, i.e. maternal triple-drug anti-retroviral treatment (ART) coupled with extended nevirapine prophylaxis to the HIV-exposed infant, to reduce the risk of vertical transmission of HIV and also identify associated factors.

Material and methods
Three hundred thirty-eight HIV-exposed infants whose polymerase chain reaction (PCR) test results were available and whose mothers received ART during October 2014 to September 2016 were studied retrospectively to determine the HIV transmission rate from mother to child. The incidence rate of HIV transmission was compared with an earlier PPTCT regimen, i.e. single-dose nevirapine mother-infant pair from a historical cohort, and preventive fractions were estimated. Univariate analysis was undertaken to identify factors associated with vertical transmission.

Results
HIV transmission was minimized significantly (26% increase in preventive fraction) with the multidrug PPTCT regimen as compared to the single-dose mother-infant pair nevirapine prophyla­xis. Other factors such as gender of infant, duration of pre-delivery ART exposure, time of HIV detection, mode of delivery, method of infant feeding, duration of nevirapine prophylaxis of the infants, etc., were not significantly associated with risk of vertical transmission when mothers were on ART.

Conclusions
Multidrug ART reduces transmission significantly with insignificant contribution of other factors, and this could pave the way towards elimination of paediatric HIV.