HomeThere are no tests available to determine if a patient has been re-infected with latent infection following exposure to a smear-positive active case. Studies primarily from the pretreatment era suggest that prior TB infection provides approximately 80% protection against development of disease following re-exposure.78,79 However, it is still uncertain whether greater intensity or duration of exposure may overcome this protective effect. This may be of particular relevance in high-TB-incidence communities, where repeated or high-intensity exposure is more likely. Further, immunocompromised people, such as people living with HIV, are likely to derive less protective benefit from prior infection.
Recommendation
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We conditionally recommend that retreatment with tuberculosis preventive treatment is usually not necessary unless the exposed person is at elevated risk of progression to TB disease (poor evidence).
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