BackgroundUptake of Isoniazid Preventive Therapy (IPT) among People Living with HIV in Zambia has continued to be low despite various evidence for its added benefit in reducing TB incidence and mortality when taken with antiretroviral therapy. In 2017, only 18% of People Living with HIV newly enrolled in care were initiated on IPT in Zambia.Main textVarious challenges including policy and management level factors, supply chain factors, health worker perceptions about IPT, monitoring and evaluation factors and limited demand creation activities have constrained the scale up of IPT in Zambia. Lessons that have been learnt while addressing the above challenges are shared and they can be applied by government ministries, project managers, public health specialists to strengthen IPT activities in their settings.ConclusionZambia has both a high burden of TB and HIV and without preventing new cases of TB from reactivation of latent TB infection, it will be difficult to control TB. All stakeholders involved in prevention of TB among PLHIV need to commit to addressing the challenges limiting scale up of IPT.

BACKGROUND: Zambia has an estimated TB incidence of 319/100,000 population and a HIV prevalence of 11.1%. In 2020, only 49% of new people living with HIV (PLHIV) received TB preventive therapy (TPT) in Zambia. Misconceptions about the reliability of symptom screening and drug resistance among people who develop TB while on TPT are barriers to TPT scale-up. We determined the incidence and predictors of breakthrough TB during TPT among PLHIV in Zambia.METHOD: This was a retrospective analysis of routine TPT programme data among PLHIV collected between October 2016 and October 2019 from select primary health facilities in Zambia.RESULTS: Of 48,581 PLHIV enrolled on TPT, 130 (0.3%) developed breakthrough TB during TPT. Of the 130, 90 client records were accessed. The median age of the breakthrough TB cases was 35 years; 68% were males. Overall, 96% of the breakthrough TB cases had been on antiretroviral therapy (ART) for 3 months; 24% were symptomatic at the beginning of TPT, 22% were asymptomatic and others had missing data. Of the 130 breakthrough TB cases, 79% developed TB in the first month after TPT initiation. The median time to TB diagnosis was 10 days (IQR 4–16).CONCLUSION: Breakthrough TB during TPT is rare among PHLIV on ART, and very rare after the first month of TPT initiation. It should therefore not be a barrier to TPT scale-up.