Tuberculosis preventive treatment (TPT) can provide strong protection against TB after treatment, but the duration of that protection may vary depending on how common the disease is in a particular setting, according to a new study.
The research, published in The Lancet Respiratory Medicine, examined TB risk among people with TB infection across 24 countries. Researchers found that preventive treatment provided strong protection during the first 12 to 24 months across countries with different levels of TB burden.
However, the study found that the protective effect could begin to decline after about one year in countries with a high burden of TB. In medium- and low-burden settings, protection was estimated to last considerably longer, with benefits continuing for at least eight and 13 years respectively.
The findings suggest that completing a course of preventive treatment does not necessarily provide the same duration of protection in every population. Continued exposure to TB infection and differences in transmission levels may influence the long-term benefit.
Researchers said countries with a high burden of TB should consider combining preventive treatment with other interventions to achieve longer-term protection. The findings therefore highlight the importance of looking beyond preventive medication alone when developing strategies to reduce TB transmission and disease.
TPT is intended for people with TB infection who do not have active TB disease, with the aim of reducing their risk of developing tuberculosis. The new study does not suggest that preventive treatment is ineffective; instead, it indicates that the level and duration of protection can differ according to the setting.
The researchers' findings could help inform TB prevention strategies in countries where transmission remains high and additional measures may be needed to sustain long-term protection.
