Incidence, time to and predictors of HIV-seroconversion among HIV Exposed infants after the first PCR: a retrospective analysis of the national EID data of 2019-2024

Abstract

Background: HIV seroconversion among HIV-exposed infants (HEIs) remains a major public health concern, particularly in settings with high maternal HIV prevalence. Despite remarkable progress in the prevention of mother-to-child transmission (PMTCT), some infants who initially test negative after birth later acquire HIV during breastfeeding. Understanding the incidence, timing, and predictors of HIV seroconversion is vital to guide interventions that strengthen Uganda’s Early Infant Diagnosis (EID) program and improve infant health outcomes. Methods: A retrospective cohort study was employed to follow-up HEI who initially tested HIV-negative on their first PCR enrolled in the national EID program. Data was obtained from the Central Public Health Laboratory (CPHL) database from 2019 to 2024. Data was cleaned and analysed using Stata version 18. The incidence rate of HIV seroconversion was computed as the number of new HIV infections per 1,000 person-months of follow-up. Time to seroconversion was estimated using Kaplan–Meier survival analysis, with the log-rank test used to compare survival distributions across subgroups. Cox proportional hazards regression was employed to identify independent predictors of HIV seroconversion Results: In this study, 59,471 HIV-exposed infants who initially tested HIV-negative at the first PCR were followed for 24 months retrospectively with 1,368 (2.3%) seroconverting during the follow-up period, yielding an overall incidence rate of 1.18 per 1,000 person-months (95% CI: 1.12–1.24). The mean time to HIV seroconversion was 10.8 months (95% CI: 10.1– 11.6), with most infections occurring within the first year of life. Multivariable Cox regression identified three significant predictors of HIV seroconversion: infant age 13–24 months [aHR: 3.1; 95% CI: 2.012–4.858; p < 0.001], poor maternal ART adherence (<85%) [aHR: 3.2; 95% CI: 2.122–4.872; p < 0.001], and unsuppressed maternal viral load [aHR: 2.4; 95% CI: 1.644– 3.539; p < 0.001]. Conclusion: The study found that while the incidence of HIV seroconversion among infants after a negative first PCR test remains low, new infections still occur primarily within the first year of life, largely attributable to inadequate maternal ART adherence and lack of viral load suppression. The findings highlight the need to reinforce maternal adherence counselling, routine viral load monitoring, and early weaning strategies aligned with PMTCT guidelines. Strengthening follow-up within the EID continuum and integrating maternal–infant pair management approaches could further reduce postnatal HIV transmission and accelerate progress toward the elimination of mother-to-child HIV transmission in Uganda.