Final answer:
Attenuated live vaccines are generally safer than inactivated vaccines, although there is a low risk of reversion to disease-causing form. Inactivated vaccines do not cause active infection and provoke weaker immune response.
Step-by-step explanation:
Attenuated live vaccines are generally considered safer than inactivated vaccines for use during pregnancy and in immunosuppressed animals, although systemic allergic reactions could still jeopardize pregnancy.
Live vaccines are made by weakening the disease-causing virus, allowing it to grow in the laboratory but inhibiting its ability to cause disease in the host. They stimulate a comprehensive immune response and can provide long-lasting immunity. However, there is a low but significant risk that these viruses may revert back to their disease-causing form by back mutations, which can lead to spread and epidemic.
Inactivated vaccines, on the other hand, do not cause active infection and usually provoke a weaker immune response. They usually require higher doses and multiple boosters, and they cannot be transmitted to others.