•Kenya is one of the 30 high burden countries that together account for more than 80 per cent of the world's TB cases.
•The WHO recommends TB preventive treatment for those at highest risk of infection, including people living with HIV and household contacts of people with TB.
A new study partly carried out in Kenya has found that the lives of 850,000 people could be saved by 2035 globally if short-course tuberculosis (TB) preventive treatment is provided to people living with HIV and contacts of individuals newly diagnosed with TB.
At least 700,000 of those lives saved would be among children aged 15 years and younger.
The study, published in The Lancet Global Health, also found the combined intervention of contact tracing and TB prevention to be broadly cost-effective for household contacts of all ages.
The impact was particularly high among children under the age of five who face higher risks of death.
Kenya is one of the 30 high burden countries that together account for more than 80 per cent of the world's TB cases.
More than 120,000 people develop TB every year and children account for 10–11 per cent of all TB cases. In 2020, TB accounted for 3.2 per cent of all deaths, per Kenya's Ministry of Health estimates.
Kenya is also one of the countries already using the short-course preventive treatment comprising the drug rifapentine.
“The imperative for TB prevention is clear,”Vincent Bretin, Director of Results at Unitaid said.
Unitaid produced some of the co-authors of the study. Other researchers came from Johns Hopkins University and the Aurum Institute.
“This cost-effectiveness analysis proves that preemptively reaching all at-risk individuals – even when it requires the logistical hurdles of going into communities to find those who may not be actively seeking care – is not just ethically sound. It is a smart investment capable of making an enormous impact on the fight to end TB worldwide.”
TB preventive therapy has made enormous strides in recent years: new shorter treatment regimens can clear TB infection before it develops into active disease with a once-weekly treatment over twelve weeks, called 3HP, or a daily treatment over one month, called 1HP.
A series of negotiations led by Unitaid, the Aurum Institute, and partners have reduced the price of treatment by more than 70% since 2017.
About one-quarter of the world’s population is infected with TB and at risk of developing active disease, which causes severe illness.
The World Health Organization recommends TB preventive treatment for those at the highest risk of infection, including people living with HIV and household contacts of people with TB.
The first United Nations High-Level Meeting in 2018 set targets to accelerate efforts to end TB as a global health threat, including a goal to reach at least 30 million people with TB preventive treatment.
Only the target to reach people living with HIV was attained, and a corresponding decrease in the number of TB cases and deaths occurred within this population during the COVID-19 pandemic.
In contrast, TB cases and deaths increased in all other populations over the same period.
“Tuberculosis remains the world’s deadliest infectious disease, despite being preventable and curable,” Professor Gavin Churchyard, Group Chief Executive Officer of the Aurum Institute said.
“Although progress has been made in preventing TB among people living with HIV, we’ve lagged behind in keeping family members—especially children—free of the disease when a parent becomes sick.
"This new study, we hope, provides the evidence needed to massively scale up the use of TB preventive treatment among those individuals at risk of developing TB.”
The study found that providing 3HP through contact tracing, in which the household members of a person diagnosed with TB are identified, assessed, and treated, could yield an estimated 13 per cent cumulative reduction in the number of contacts developing TB through 2035 and an estimated 35 per cent cumulative reduction in deaths.
Among children under five, the combination of 3HP with contact tracing showed to have a profound impact on the child TB burden overall, helping to drive up the identification of active disease in addition to preventing new infections.
The impact of missing cases among this population was so substantial that the intervention would save more lives by treating TB disease and infection than the number of new infections prevented.
The study is the first to provide comparable evidence on the cost-effectiveness of short-course TB preventive treatment for people living with HIV and household contacts in three age groups (< 5, 5-14, and ≥ 15 years old), using consistent methods for all four populations.
This provides a clear justification to support policy change and implementation of the life-saving approach where coverage is lagging.
“At the moment, too many family members of people diagnosed with TB are slipping through the cracks and too many lives are being lost,” Tess Ryckman, faculty member at Johns Hopkins University and lead author of the study said.
“To finally make a significant dent in the TB epidemic, we need stronger recommendations in favor of TB prevention for household contacts along with a significant boost in resources. The stakes are too high not to act now.”
Despite the cost-effectiveness of TB preventive treatment, the researchers note that the absolute cost of scale up will be substantial. External funding—with an explicit plan to bridge to domestic support as TB burden declines—will be needed, as well as a further decrease in the price of the drug rifapentine, the key cost driver in short TB prevention regimens.