They are indications of a systemic BCG reaction, and further administration is immunosuppressive and potentially lethal. A urine culture should be obtained because many cases of septicemia following BCG vaccine instillation are caused by more common uropathogens, rather than the organisms in the BCG vaccine.

Does BCG affect your immune system?

They showed that administering BCG to the mice resulted in increased numbers of immune cells called T cells in the tumor. Immunity to this cancer could be transferred from one mouse to another by transferring these T cells — but only if the first mouse had cancer.

Does BCG treatment for bladder cancer affect the immune system?

Intravesical BCG

While it doesn't usually cause a person to get sick, it can help trigger an immune response. BCG can be put right into the bladder as a liquid. This activates immune system cells in the bladder, which then attack bladder cancer cells.