The primary objective is to assess the safety of two doses of C-Tb (0.01 and 0.1 µg/0.1 mL) when administered intradermally by the Mantoux technique to patients in the acute phase of treatment against active TB. The secondary objectives are to assess the immune response of two doses (0.01 and 0.1 µg/0.1 mL) of C-Tb from the size of induration and to assess the safety of unpreserved C-Tb and C-Tb preserved with 0.5% phenol (local reactions).

This clinical trial is a single centre phase Ib open dose adjustment study with respect to the dose of C-Tb combined with a double blind randomised, split-body comparison of unpreserved C-Tb and C-Tb preserved with 0.5% phenol (each patient receives the unpreserved version in one arm and the preserved version in the other arm).

Inclusion Criteria:

The patient:

1. Has signed an informed consent

2. Is willing and likely to comply with the trial procedures

3. Has been diagnosed with active TB and has been in treatment ≤ 60 days at the time of inclusion

   • has 1 documented positive sputum smear microscopy result
   • has positive culture
   • has a positive PCR result for tuberculosis
   • has a compatible clinical picture of TB with the intention to treat

4. Has a positive T-spot assay or a QuantiFERON®-TB Gold In Tube test

5. Is prepared to grant authorized persons access to their medical records

Exclusion Criteria:

The patient:

1. Has been in treatment with a product which is likely to modify the immune response within 3 months prior to the day of inclusion (e.g., immunoglobulin, systemic corticosteroids, methotrexate, azathioprine, cyclosporine or blood products)
2. Has been vaccinated with a live vaccine within 6 weeks prior to the day of inclusion (e.g. BCG, MMR, yellow fever, oral typhoid vaccines)
3. Has a known congenital or acquired immune deficiency
4. Has a disease affecting the lymphoid organs (e.g., Hodgkin's disease, lymphoma, leukaemia, sarcoidosis)
5. Is infected with HIV
6. Has severe scarring, burn, rash, eczema, psoriasis, or any other skin disease at or near the injection sites
7. Has a condition where blood drawings pose more than minimal risk for the patient, such as haemophilia, other coagulation disorders, or significantly impaired venous access
8. Is actively participating in another clinical trial
9. Is pregnant according to urine pregnancy test at inclusion
10. Has a condition which in the opinion of the investigator is not suitable for participation in the study