Why is a live virus vaccine more dangerous then other ones?

A live virus vaccine is considered more dangerous than inactivated or subunit vaccines because it contains a weakened form of the virus that can potentially replicate in the host. This replication may lead to mild or, in rare cases, severe illness, especially in immunocompromised individuals. Additionally, there is a small risk that the live virus could revert to a virulent form. However, the benefits often outweigh these risks as live vaccines generally provide strong and long-lasting immunity.