Who is contraindicated for live vaccines?

Live vaccines contain weakened forms of the virus or bacteria they are designed to protect against. While this weakness allows the immune system to respond and build immunity, it can also pose a risk to certain populations whose immune systems may not be able to handle even a weakened pathogen.

Pregnant women are particularly at risk because their immune systems are naturally suppressed to protect the developing fetus. Administering a live vaccine could potentially harm the fetus by either causing a mild infection or provoking an immune reaction that could affect pregnancy. For this reason, pregnant women are advised to avoid live vaccines during their pregnancy.

In contrast, infants under 1 year old can receive some live vaccines, such as the measles, mumps, and rubella (MMR) vaccine, typically at 12 months. Healthy adults usually tolerate live vaccines well, as their immune systems are generally robust enough to manage the weakened agent. Elderly individuals often have waning immunity but are also generally able to receive live vaccines unless they have other contraindications.