Why are live attenuated vaccines generally contraindicated in severely immunocompromised individuals?

• A. They are less effective in immunocompromised, so not recommended.
• B. They can replicate and cause disease due to impaired immune control.
• C. They require additional boosters.
• D. They are more expensive.

Answer: (B)

Live attenuated vaccines use weakened forms of pathogens that can still replicate enough to trigger a strong immune response. In people with severe immunocompromise, the immune system is not able to control even these weakened organisms. That means the vaccine strain could multiply and cause disease itself, or spread within the body, leading to serious illness. This safety risk is why live attenuated vaccines are generally avoided in severely immunocompromised individuals.

The other ideas—that they’re less effective, require boosters, or cost more—don’t capture the primary concern. The key point is safety: the potential for the weakened organism to cause disease when immune defenses can’t contain it.