Which individuals are at an increased risk of adverse effects from live vaccines?

Immunocompromised individuals are at an increased risk of adverse effects from live vaccines because their immune systems are less capable of handling the live attenuated viruses or bacteria contained in these vaccines. Live vaccines are designed to stimulate a strong immune response, but in someone with a weakened immune system—whether due to a medical condition such as HIV/AIDS, cancer, or treatment with immunosuppressive therapies—the body may not adequately control the attenuated pathogen. This can lead to severe infections or other complications that healthy individuals would not typically experience.

Children under 5 years old, while they do receive vaccinations, are generally not at heightened risk for adverse effects from live vaccines compared to immunocompromised patients. Similarly, pregnant women are usually advised to avoid live vaccines due to potential risks to the fetus, but they are not at an increased risk of adverse effects from the vaccine itself in the same way that immunocompromised individuals are. Individuals over 65 years old might have other age-related risks but do not have the specific vulnerability that comes with immunosuppression when it comes to live vaccines. Thus, the unique situation of immunocompromised individuals makes them particularly susceptible to adverse effects from live vaccines.