Which of the following is considered a live but modified vaccine?

The choice of MMR (Measles, Mumps, Rubella) as a live but modified vaccine is grounded in the nature of how the vaccine is designed and its mechanism of action. Live modified vaccines, also known as live attenuated vaccines, are made from organisms that have been weakened so they cannot cause disease in healthy individuals. However, they still evoke a strong immune response.

In the case of the MMR vaccine, it contains live attenuated viruses for measles, mumps, and rubella. These viruses have been specifically altered to reduce their pathogenicity while maintaining their ability to trigger an immune response. This effective immunization strategy allows the body to recognize and combat the actual viruses if exposed in the future, providing long-lasting immunity.

In contrast, the other options listed are inactivated or subunit vaccines. IPV (Inactivated Polio Vaccine) uses killed virus particles and does not provide the same breadth of immune response as a live vaccine. Tdap (Tetanus, Diphtheria, and Pertussis) is a vaccine that contains inactivated toxins or subunit components rather than live organisms. Hepatitis B vaccine is a recombinant subunit vaccine that uses a piece of the virus to induce immunity without employing live