Is it a problem if I haven't received the BCG vaccine by age 24?

Generally, it is not a serious issue if the BCG vaccine has not been administered by age 24; proper daily care and precautions are sufficient. The specific analysis is as follows:

The BCG vaccine is a live bacterial vaccine made from a suspension of attenuated bovine tuberculosis bacilli. It helps enhance the ability of macrophages to kill tumor cells and strengthens the body's cellular immune function, thereby helping prevent tuberculosis, common colds in children, and other diseases. It is typically recommended to receive the BCG vaccine within 24 hours after birth. However, at 24 years of age—an adult with a relatively mature and robust immune system—missing the BCG vaccination is usually not a major concern.

It is advisable to maintain good daily protection: avoid contact with tuberculosis patients, ensure adequate nutrition, exercise appropriately, strengthen physical health, and reduce the risk of infection.