The vaccine used to plant the flowers on your arm is the BCG vaccine, which is used to prevent tuberculosis infection. BCG is a live vaccine prepared from attenuated bovine tubercle bacilli, which, when inoculated into the body, stimulates the immune system and prevents infection by tubercle bacilli. After BCG vaccination, the localized inoculation site will go through the process of redness, swelling, pustules, breakage and scabbing, eventually forming a permanent indented scar in the area. Babies should not be vaccinated with BCG when they are suffering from tuberculosis or other acute infectious diseases, low body weight, immunodeficiency, jaundice, diarrhea, and other diseases. After BCG vaccination, some children may have adverse reactions such as fever, which can be treated with fever reduction. If there are enlarged lymph nodes, ulceration at the site of vaccination, or co-infection, they should go to the hospital for treatment.