There is always a risk of HIV-positive mothers passing the infection to their children. But a new study has found that common antiviral drugs can almost completely stop this transmission.

The study, published in the journal The Lancet HIV, was conducted by researchers from Karolinska Institutet, Sweden. The study showed there was less than a 2% chance of a mother on antiviral treatment passing on the HIV infection to her children.

The study gained more importance since it was able to reduce transmission rates even in a low-income country with a high HIV incidence such as Tanzania.

"HIV transmission from mother to child can in principle be stopped completely with modern antiviral drugs. But so far it has not been demonstrated in low-income countries in Africa with a high incidence of HIV infection," first author, Goodluck Willey Lyatuu, physician and postdoctoral researcher at the Department of Global Public Health at Karolinska Institutet, said, reported MedicalXpress.

The findings provide a shot in the arm for the World Health Organization's goal of completely stopping the transmission of HIV infection from mother to child.

UNAIDS, a UN organization, says that the chances of children born to HIV-positive mothers in Tanzania, due to infection in the womb, during childbirth, or via breast milk, is 11%. The new study lowers the estimate significantly.

The researchers followed more than 13,000 HIV-positive, pregnant women, in one of Africa's largest cities, Dar es Salaam, in Tanzania. These women were on antiviral treatment as part of maternity care between 2015 and 2017.

The women and the children were followed for 18 months after birth, a time when most of the mothers had stopped breastfeeding. Surprisingly, only 159 children were found to be infected with the virus.

Factoring in the margin error, this roughly translates to a risk of only 1.4%.

"It is one of the largest cohort studies published from Africa on the risk of HIV transmission from mother to child where the baby is followed until the end of the breastfeeding period," co-author, Anna Mia Ekström, clinical professor at the Department of Global Public Health at Karolinska Institutet, said, according to the outlet.

The risk of infection was not evenly distributed. It was more than double in women who received treatment late in pregnancy or were at advanced stages of HIV. In the same way, the risk of infection was found to be just 0.9% in women who had already received the treatment when they became pregnant.

While the overall chances of infection were found to be minimal, Anna Mia Ekström warned that "it is still important to improve early HIV diagnosis, optimize follow-up measures, and offer specialist support to young mothers."