Infant HIV Testing in Nigeria: Study Links Feeding Method to Antibody Timelines

Researchers followed babies receiving care at the Nigerian Institute of Medical Research in Yaba, Lagos, to investigate when their rapid antibody tests became negative. The research found that more than half had reached this point by 24 weeks, with feeding method showing the clearest connection to timing.

A positive HIV antibody test in a young baby can be frightening for parents, particularly when the result needs careful explanation rather than an immediate diagnosis. Babies born to mothers living with HIV can carry antibodies passed to them during pregnancy without having the infection themselves. Understanding when these inherited antibodies fall below a test's detection limit can help families make sense of changing results during follow-up care.

The study, "Time to seroreversion among HIV exposed infants in Lagos, Nigeria: a prospective cohort study," published in Frontiers in Pediatrics, examined this process in 111 mother–infant pairs. Researchers followed babies receiving care at the Nigerian Institute of Medical Research in Yaba, Lagos, to investigate when their rapid antibody tests became negative. The research found that more than half had reached this point by 24 weeks, with feeding method showing the clearest connection to timing.

The change from a positive antibody result to a confirmed negative result is called seroreversion, a term describing a testing change rather than recovery from HIV. All infants in this study were reported as HIV-uninfected through HIV DNA testing, which looks for evidence of the virus itself. The findings address an important challenge in settings where the cost of laboratory testing, supply shortages and pressure on health services can disrupt early infant diagnosis.

How the researchers followed babies in Lagos

The study ran from February 2020 to March 2023 at a clinic providing services to prevent HIV transmission from mothers to babies. Of 130 mother–infant pairs screened, 111 entered the study, including 68 babies exclusively breastfed and 43 receiving breast milk substitutes during their first six months. All mothers were receiving antiretroviral treatment, and all enrolled infants had received preventive antiretroviral medication.

Scheduled rapid antibody tests took place at 6–8 weeks and at 3, 6, 9, 12, 15 and 18 months. Researchers recorded seroreversion at the first negative test when a second negative result confirmed it at the next visit. HIV DNA PCR testing was performed at six weeks, with another test six weeks after breastfeeding stopped for breastfed infants.

The team collected information on birth weight, delivery circumstances, feeding, maternal treatment, viral load and immune health to explore possible influences on antibody-test timing. Eligibility rules excluded babies arriving for their first visit at eight weeks or later, those born at 34 weeks or earlier, and those weighing 2 kilograms or less, among other exclusions. These criteria matter because the findings describe a selected group receiving organised follow-up care.

More than half reached seroreversion by 24 weeks

During follow-up, 103 infants had confirmed seroreversion, seven were lost to follow-up, and one died from a cause unrelated to HIV. The analysis retained information from the eight infants with incomplete follow-up up to their last antibody test. The median age at seroreversion was 24 weeks, with an estimated uncertainty range of 24–32 weeks.

Seven babies had already seroreverted by six weeks, showing that the change could occur early in infancy. The estimated cumulative probability of seroreversion reached 20.0% by 12 weeks, 54.6% by 24 weeks and 87.8% by 36 weeks. Among the 103 babies with confirmed seroreversion, 12 reached that point after 36 weeks, highlighting the variation between children.

Researchers described earlier seroreversion than several previous studies had reported, with results close to one study from Malawi. Differences in antibody tests, maternal treatment, study methods and clinical settings make direct comparisons difficult. The researchers suggested that effective maternal treatment and low viral levels could help explain earlier negative results, a possibility they could not directly establish without measurements of antibody concentrations.

Feeding method showed the clearest link to timing

Babies receiving breast milk substitutes reached seroreversion at an average age of 21.7 weeks, compared with 27.7 weeks among exclusively breastfed babies. The median ages were 24 weeks and 32 weeks, respectively. By 24 weeks, the estimated proportion reaching seroreversion was 75.3% in the substitute-fed group and 41.5% in the exclusively breastfed group.

The feeding association remained present after researchers accounted for other measured factors and checked their findings using alternative analyses. Their main adjusted model produced a hazard ratio of 2.77, a measure indicating earlier seroreversion in the substitute-fed group rather than a 2.77-fold reduction in HIV infection risk. An analysis accounting for the gaps between testing visits supported the same pattern, with no clear evidence that the association differed across age periods.

This observational study cannot establish that feeding method caused the difference or that earlier antibody negativity represents better health. An initial association with maternal protease inhibitor treatment was less consistent across analyses, and findings involving birth weight and maternal CD4 counts did not survive corrections for multiple comparisons. Infant sex, gestational age, delivery method and other measured factors showed no convincing independent association with timing, and exploratory viral-load findings remained uncertain.

What the findings mean for infant HIV care

The research offers information that could help improve testing schedules and interpretation of rapid antibody results in clinics with limited resources. Earlier antibody negativity does not turn a rapid antibody test into a replacement for HIV DNA testing, which the paper identifies as the standard for early infant diagnosis. The feeding findings alone do not justify recommending a change in how babies are fed.

The study's strengths included following infants forward in time and testing fresh samples during routine care. Its limitations included a small sample from one centre, missing information, missed appointments, disrupted recruitment during COVID-19 and the absence of details about maternal treatment duration and antibody concentrations. The sample size was designed to estimate a proportion rather than support complex comparisons involving many possible influences.

Using one rapid test means the results describe antibodies falling below that test's detection threshold, rather than proof that every maternal HIV antibody had disappeared. Larger studies involving different clinics and testing methods would help establish how widely these timelines apply. The paper's central message supports comprehensive care that brings together maternal treatment, infant prevention, reliable diagnostic testing and continued follow-up.