I'm an HHD patient, but I've had in-center treatments at DaVita dialysis clinics while on business trips in the Denver, CO area, Greenville, SC, Olathe, KS and Kansas City, MO. I've never observed patients receiving TB shots during their treatments. As an HHD patient, my HHD clinic has to administer a TB test once per year for each patient on their HHD program. This is generally done with a subcutaneous injection of the TB antigen, and one week later the injection site must be "read" for a positive reaction, e.g. the presence of the TB virus. The alternate test is through a blood draw into several blood collection tubes that contain some material that will react to the presence of the TB virus. The treatment for TB is typically antibiotics in steady doses, so the every 3 months regimen doesn't seem to match up. It's more like the patients are being screened for TB. The three month screening schedule seems rather excessive, unless one or more patients at that clinic were diagnosed with TB and this is an ongoing precaution for the remaining patients.