Why Corona vaccine is not permanent?

The development of a vaccine for any virus is a complex process, and the development of a vaccine for the novel coronavirus is no exception. Vaccines work by introducing a weakened or inactivated form of the virus into the body, which then stimulates the body's immune system to create antibodies that can fight off the virus if it is encountered again. However, the effectiveness of a vaccine can vary depending on the virus, and the novel coronavirus is still relatively new, so it is not yet known how long the immunity provided by a vaccine will last. Additionally, the virus is constantly mutating, so it is possible that the immunity provided by a vaccine may not be effective against new strains of the virus.