What are risks of live attenuated vaccines?

Anthony L. Komaroff, MD
Internal Medicine
Live attenuated vaccines contain a live microbe that is weakened in such a way that it can no longer cause disease. However, the attenuated form of the pathogen in the vaccine could mutate (just as any other living organism can mutate) and regain the ability to cause the disease. This risk is extremely small in healthy people, but greater in people whose immune systems are already compromised. For this reason, people with cancer or those infected with human immunodeficiency virus (HIV) shouldn't receive live attenuated vaccines.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.