Introduction: Viral load (VL) of 1000 copies/ml or greater is commonly used to define virologic failure (VF) in children and adolescents living with HIV (CALHIV) in low- and middle-income countries (LMICs). However, evidence in adults suggests that low-level viraemia (LLV) (VL 50-999 copies/ml) increases the risk of subsequent VF. There is limited research on LLV in CALHIV.

Methods: This study retrospectively reviewed VL data from Baylor College of Medicine Children's Foundation-Tanzania (sites in Mbeya and Mwanza) collected between January 2015 and December 2022. CALHIV (0-19 years) on antiretroviral therapy for ≥6 months with at least one VL <50 copies/ml plus ≥2 subsequent VLs were included. VF was defined as both VL ≥1000 and ≥200 copies/ml. Multivariable Cox regression models were used to assess the association between LLV and VF, reporting adjusted hazard ratios (aHR) with 95% confidence intervals (CI).

Results: Among 2618 CALHIV included in the outcome analysis (median age 13.2 years, 52.5% female), 81.9% were on first-line dolutegravir-based regimens and LLV was found in 40.5%. CALHIV with LLV had an increased risk of VF with aHRs of 1.63 (CI 1.38-1.91) (VL ≥1000 copies/ml) and 3.85 (3.33, 4.46) (VL ≥200 copies/ml). When stratifying by LLV (50-199, 200-399 and 400-999 copies/ml), all levels were associated with increased risk for VF (VL ≥1000 copies/ml) with aHRs of 1.39 (1.13, 1.69), 1.69 (1.33, 2.16) and 2.03 (1.63, 2.53). When VF was defined as VL ≥200 copies/ml, the corresponding aHRs were 1.41 (1.15, 1.72), 7.99 (6.68, 9.57) and 9.37 (7.85, 11.18).

Conclusions: LLV is associated with a greater risk of VF in CALHIV. The risk of VF increases with higher levels of LLV. This study provides further evidence for revising guidelines in LMICs that define VF as VL ≥1000 copies/ml.

Keywords: HIV; paediatric; sub‐Saharan Africa; treatment failure; viraemia; virologic failure.

© 2025 The Author(s). Journal of the International AIDS Society published by John Wiley & Sons Ltd on behalf of International AIDS Society.

引言： 在低收入和中等收入国家（LMICs）生活着的儿童和青少年艾滋病患者（CALHIV）中，通常将病毒载量（VL）≥1000 copies/ml 用于定义病毒学失败（VF）。然而，成人证据表明，低水平病毒血症（LLV，即 VL 50-999 copies/ml）会增加后续 VF 的风险。关于 CALHIV 中 LLV 的研究有限。

方法： 本研究回顾性分析了贝勒医学院儿童基金会—坦桑尼亚（姆贝拉和姆万扎站点）2015 年 1 至 2022 年 12 月期间收集的病毒载量数据。入选对象为接受抗逆转录病毒治疗至少六个月且至少有一次 VL

结果： 在纳入结局分析的 2618 名 CALHIV 中（中位年龄为 13.2 岁，52.5% 是女性），81.9% 的人使用一线多替拉韦为基础的治疗方案，LLV 发生率占 40.5%。CALHIV LLV 病毒载量水平较高会增加 VF 的风险，aHRs 分别为 1.63（CI 1.38-1.91）（VL ≥1000 copies/ml）和 3.85 (3.33, 4.46) （VL ≥200 copies/ml）。按照 LLV 水平分类（50-199，200-399 和 400-999 copies/ml），所有水平都与 VF 风险增加有关 (VL ≥1000 copies/ml)，aHRs 分别为 1.39 (1.13, 1.69)，1.69 (1.33, 2.16) 和 2.03 (1.63, 2.53)。当 VF 定义为 VL ≥200 copies/ml，对应的 aHRs 分别为 1.41（1.15-1.72），7.99（6.68-9.57）和 9.37（7.85-11.18）。

结论： 低水平病毒血症与 CALHIV 中 VF 的风险增加有关。VF 风险随着 LLV 水平的升高而增大。本研究为修订在 LMICs 将 VF 定义为 VL ≥1000 copies/ml 的指南提供了进一步证据。

关键词： HIV；儿科；撒哈拉以南非洲；治疗失败；病毒血症；病毒学失败。

© 2025 The Author(s). Journal of the International AIDS Society published by John Wiley & Sons Ltd on behalf of International AIDS Society.