What should you know about the BCG live attenuated vaccine?

“Live attenuated” means the microorganism has been weakened so it can stimulate immunity without behaving like the usual disease-causing form in a healthy person. BCG is used in selected vaccination programmes to reduce the risk of serious tuberculosis. It is different from vaccines such as MMR, chickenpox, and yellow fever, although those are also examples of live attenuated vaccine approaches.

The choice and timing of a live vaccine depend on age, health, travel or exposure plans, pregnancy, and immune-system function. A small local reaction can occur after BCG and may change over time as it heals.

Tell the vaccinator about immune suppression, recent treatment, pregnancy, serious allergies, and previous vaccine reactions. Bring your immunisation record and ask how to care for the injection site. Do not squeeze, scratch, or cover a BCG site with an unapproved product. If a dose has been delayed, ask how to continue rather than making assumptions about restarting or repeating it.

Seek emergency help for breathing difficulty, facial or throat swelling, collapse, or a widespread rapidly developing rash after vaccination. Contact a healthcare professional if the BCG site becomes increasingly painful, hot, swollen, heavily draining, or fails to heal as expected, or if the recipient develops persistent fever or appears very unwell. Extra caution is needed when the immune system is weakened.

Ask why BCG is recommended, how a live attenuated vaccine differs from other vaccine types, what reaction is expected at the site, and which health conditions change the advice.