Zero vertical transmissions from over 5000 pregnant women with undetectable HIV in France

Data collected since the year 2000 show an HIV transmission rate of 0% among women who were taking HIV treatment at the time of conception, had an undetectable viral load at childbirth and did not breastfeed, the National French Perinatal Cohort reports to the Conference on Retroviruses and Opportunistic Infections (CROI 2022).

The statement ‘undetectable equals untransmittable’ (U=U) is based on data on sexual transmission, not vertical transmission. Nonetheless, the French report shows what is possible in a high-income country with uninterrupted access to health care.

“In the absence of breastfeeding, and in the French context of free access to antiretroviral therapy and monthly plasma viral load assessment, suppressive antiretroviral therapy initiated before pregnancy and continued throughout the pregnancy can eliminate perinatal transmission of HIV,” say Dr Jeanne Sibiude and colleagues.

Between 2000 and 2017, there were 15,959 live births to mothers living with HIV-1 in mainland France in the cohort. Excluded from the analysis were 37 infants who were breastfed and 1292 infants who were lost to follow-up. Data were collected up to two years of age.

The 0% figure relates to the 5482 infants whose mothers were already taking HIV treatment when they became pregnant, had an undetectable viral load (below 50) at the time of delivery and did not breastfeed. In addition, there was a 0% transmission rate for 2358 infants whose mothers were undetectable during the first trimester of pregnancy.

The study shows changes over time. The proportion of women receiving HIV treatment increased from 68% in 2000-2005 to 99.2% in 2011-2017, as did the proportion taking it at the time of conception (from 28% to 66%) and the proportion who had an undetectable viral load at delivery (from 70% to 93%).

Perinatal transmission rates decreased steadily, from 1.1% in 2000-2005 and 0.7% in 2006-2010, to 0.2% in 2011-2017. The figure in the latter time period corresponds to ten infants out of a total of 4907 – in other words, 1 in 490 of all non-breastfed infants acquired HIV.

The data confirm the circumstances in which vertical transmissions occur:

• Transmission was frequent when the mother did not receive treatment (8.3%).
• The earlier treatment was started, the rarer transmission was (0.1% before conception, 0.5% in the first trimester, 0.8% in the second trimester and 1.7% in the third trimester).
• While there were zero transmissions with a viral load below 50, the rate was 0.2% with a viral load between 50 and 400, and 2.4% above 400.
• Premature delivery also increased the risk, with a rate of 1.3% for babies delivered between 32 and 36 weeks and 2.1% for those delivered before 32 weeks.