Which of the following statement about lepromin test is not true?
The lepromin test is used to study host immunity to M.leprae.
The test was first described by Mitsuda in 1919. The test is an intradermal skin test performed by using lepromin antigen, which is a suspension of killed M. leprae obtained from infected human or armadillo tissue.
The lepromin test is not used to confirm the diagnosis of leprosy. It is also not useful to indicate prior contact of the person with leprae bacilli. Healthy people residing in areas nonendemic for leprosy with no chance of contact with the bacilli may show a positive lepromin reaction.

Key Points:-
The lepromin test is used mainly to:

Determine the type of leprosy, being positive (suggests resistance to disease) in tuberculoid leprosy and negative (suggests a lack of resistance to the disease) in lepromatous leprosy patients.
Monitor the response of leprosy patients to treatment with chemotherapy. A positive reaction indicates a good prognosis, while a negative test suggests a very bad prognosis.
Evaluate host resistance to leprosy.

Parija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page: 368
It is negative in most children in first 6 months of life
It is a diagnostic test
It is an important aid to classify type of leprosy disease
BCG vaccination may convert lepra reaction from negative to positive