 For example, a low-risk patient must have a larger induration for a positive result than a high-risk patient.High-risk groups include recent contacts, those with HIV, those with chest radiograph with fibrotic changes, organ transplant recipients, and those with immunosuppression.According to the Ohio Department of Health and US Department of Health, the Bacillus Calmette–Guérin (BCG) vaccine does not protect against TB infection.