How long does the BCG vaccine for newborns cause abscess formation?

Patient's question:

No

Doctor's answer:

Generally, about 2 weeks after receiving the BCG vaccine, local redness and infiltration may appear. If it subsequently becomes purulent and forms a small ulcer, gentian violet (1%) can be applied to prevent infection. Typically, it takes 8-12 weeks for the scab to form. The hepatitis B vaccine is relatively painful, which is a normal reaction and nothing to worry about.