Subpopulations Although the data were limited, based on the available evidence, the GDG members supported extrapolation of the recommendation for the following populations:

• PLHIV;
• children and adolescents aged under 18 years; and
• people who have been vaccinated with BCG. For all the above-mentioned subpopulations, TBSTs are recommended. Testing for TB infection is not a precondition for initiating TPT among and children under 5 years of age who are household contacts of people with active TB. Nevertheless, testing for TB infection increases the certainty that individuals will benefit from TPT.

Implementation considerations Considerations for implementation were as follows:

• regulatory approval from national regulatory authorities or other relevant bodies is required before implementation of in vivo diagnostic tests;
• appropriate communication on the new class of tests is necessary, highlighting the difference between the TST and TBSTs;
• implementation of TBSTs requires a cold chain;
• well-trained skilled staff are needed to administer and interpret this class of tests;
• multiuse vials will require effective operational planning and batching; hence, single-use vials or vials with fewer doses to match daily needs are preferred;
• procurement and stock management aspects will have to be considered, as with implementing any new class of tests;
• because the reading of the TBST results requires a second patient visit, linkage to care requires reinforcement, to decrease loss to follow-up;
• global market availability and necessary volumes of the new class of tests must be considered; and
• measurement of the TBST reaction size and interpretation must be standardized.