Lifelong access to antiretrovirals nearly eliminates risk for vertical HIV transmission

In Tanzania, pregnant women with HIV who had access to antiretroviral therapy for life had less than a 2% risk for vertical transmission, according to data published in The Lancet HIV.

Although 84% of pregnant Tanzanian women with HIV had access to antiretroviral therapy (ART) in 2020, the estimated risk for vertical transmission was 11.1%, according to study background.

“HIV transmission from mother to child can in principle be stopped completely with modern antiviral drugs,” Goodluck Willey Lyatuu, PhD, a physician and postdoctoral researcher at the department of global public health at Karolinska Institutet in Stockholm, said in a press release. “But so far it has not been demonstrated in low-income countries in Africa with a high incidence of HIV infection.”

Enrolling participants

From 2015 to 2017, Lyatuu and colleagues prospectively enrolled 13,251 pregnant women (median age, 30 years) with HIV who presented to 226 health care centers in Dar es Salaam, Tanzania, in a program providing care to prevent vertical HIV transmission. The researchers followed each mother-infant dyad for 18 months after delivery using data collected at routine monthly visits. The last database follow-up was conducted March 31, 2021.

The primary outcome was infant HIV diagnosis confirmed by DNA polymerase chain reaction or positive antibody test.

In total, 6,072 (45.8%) women were already on ART and 7,179 (54.2%) began ART at enrollment. Among 10,866 women who had data on gestational age at enrollment, 7,106 (65.4%) were in their second trimester and 1,850 (17%) were in their third trimester. More than one in four women (n = 3,691; 27.9%) had advanced HIV.

Rates of vertical transmission

During 18 months of follow-up, 13,251 (1.4%) infants were diagnosed with HIV (95% CI, 1.2-1.6). Most diagnoses (n = 107; 67.3%) were made within 3 months after delivery.

Infants of women already on ART were at a lower risk for diagnosis compared with those born to women who began ART upon enrollment (adjusted HR = 0.39; 95% CI, 0.25-0.6). The risk for vertical transmission was also lower among women who attended high-volume vs. low-volume clinics (aHR = 0.46; 95% CI, 0.24-0.9).

Further analyses revealed that the rate of vertical transmission was higher among women who enrolled during the third vs. first trimester (aHR = 3.01; 95% CI, 1.59-5.7), as well as among women with advanced vs. early-stage disease (aHR = 1.89; 95% CI, 1.22-2.93) and among women on a second- vs. first-line ART regimen (aHR = 3.58; 95% CI, 1.08-11.82).

Notably, female infants had a greater risk for vertical transmission compared with male infants (aHR = 1.49; 95% CI, 1.06-2.1).

“Our findings underscore the need to accelerate early HIV diagnosis and ART linkage in women (and men) of reproductive age, as well as primary HIV prevention particularly of incident infections in HIV-negative pregnant women at increased risk of HIV (eg, those with HIV-positive sexual partners or partners with unknown HIV status, or women who engage in high-risk sexual behaviors),” Lyatuu and colleagues wrote. “These findings also emphasize the importance of strengthening risk stratification, management and follow-up of infants at high risk exposed to HIV.”

References:

• Common medicine can stop the transmission of HIV infection from mother to child. news.ki.se/common-medicine-can-stop-the-transmission-of-hiv-infection-from-mother-to-child. Published Dec. 8, 2022. Accessed Dec. 8, 2022.
• Lyatuu GW, et al. Lancet HIV. 2022;doi:10.1016/S2352-3018(22)00289-2.