Compared to inactivated vaccines, live attenuated vaccines tend to have higher rates of adverse effects (particularly fever). Potentially, vaccines containing live attenuated viruses can also infect the fetus. Vaccines containing live attenuated viruses should only be administered to pregnant women if there is a high immediate risk of infection by a specific pathogen, e.g., a poliomyelitis epidemic. The same precaution applies to individuals with a compromised immune system (Box 2).
