Landon Myer, MD, PhD, on Elevated Viral Loads Among Pregnant Women With HIV Initiating ART

Drug-resistance mutations may elevate the viral loads of pregnant women with HIV who are initiating antiretroviral therapy (ART) during pregnancy, according to new research.1

To find out more about this research and its findings, Consultant360 contacted lead author Landon Myer, MD, PhD, who is professor of Epidemiology and Biostatistics and head of the School of Public Health & Family Medicine at the University of Cape Town in South Africa.

Here are his answers to our questions.

CON360: For your study, you and your colleagues examined the viral loads of a cohort of women with HIV who initiated ART during pregnancy (N=628). Can you tell us more about your study and its findings?

Landon Myer: We followed a cohort of over 600 women living with HIV in Cape Town, South Africa, from the beginning of their antenatal care through 18 months postpartum. All the women started ART during pregnancy; with daily adherence, ART suppresses HIV viral load, which in turn reduces the risk of mother-to-child transmission and improves the health of mothers over time. However, previously we had found that many of these women had experienced a raised viral load—around 30% of the cohort had a viral load of more than 1000 copies/mL during the postpartum period, even after they had suppressed their viral load early after starting ART in pregnancy.

So in this study, we asked, “What is causing the raised viral loads we see in this setting?” To answer this, we conducted a case-control study in 167 women, nested within the larger cohort, using stored specimens collected from the women over time. We tested specimens taken from women before they started ART, specimens from the time they had suppressed viral load on ART, and specimens from the time they had raised viral load. We tested specimens for antiretroviral drug levels and for DRMs. We found that the levels of DRMs were relatively low pre-ART—about 8% to 10% of the cohort had any kind of DRM before they started treatment. If women had a DRM pre-ART, they were slightly more likely to experience raised viral load while taking ART. However, DRMs only explained a very small fraction of the raised viral loads we saw over time; the vast majority of raised viral loads was caused by women simply not taking their ART, as reflected in the levels of antiretroviral drugs in their blood. 

CON360: Taken together, what do the findings from your study mean for clinical practice and how HIV might be managed in pregnancy in the future?

LM: We know that all over the world, many pregnant and postpartum women with HIV experience elevated viral loads despite using ART. This study helps demonstrate clearly that nonadherence to therapy is the driver of raised viral loads. DRMs, while important, only explain a small proportion of all the elevated viral loads we see at a population level—it is really all about nonadherence.

CON360: What knowledge gaps still exist regarding the treatment of HIV among pregnant women?

LM: The big knowledge gap right now is how this may be different with new antiretroviral drugs. We did this study among patients using non-nucleoside reverse transcriptase inhibitor (NNRTI)-based therapy, but now all over the world people are moving to integrase strand transfer inhibitor (INSTI)-based treatment. Will the findings look different? Will adherence be better in this patient population? No one knows for sure, and it is a critical issue to keep an eye on.

CON360: What is the overall key take-home message for public health providers?

LM: Women with HIV may be challenged to maintain high levels of adherence to ART, especially in the postpartum period; many women will benefit from special attention and support from health care providers.



  1. Myer L, Redd AD, Mukonda E, et al. Antiretroviral adherence, elevated viral load, and drug resistance mutations in human immunodeficiency virus–infected women initiating treatment in pregnancy: a nested case-control study. Clin Infect Dis. 2020;70(3):501-508.