Final answer:
The Measles, mumps, and rubella (MMR) vaccine is contraindicated for a 12-month-old immunocompromised infant because it contains a weakened version of the live virus, posing a potential infection risk for the patient.
Step-by-step explanation:
The nurse reviewing the immunization records of a 12-month-old immunocompromised infant should identify the Measles, mumps, and rubella (MMR) vaccine as contraindicated for this patient. This vaccine is a live attenuated vaccine, which means it contains a weakened version of the live virus. It is generally contraindicated in immunocompromised individuals due to the potential risk of the vaccine strain causing infection. In contrast, vaccines like Hepatitis A (Hep A), Pneumococcal conjugate (PCV13), and Haemophilus influenzae type B (Hib) do not contain live viruses and are considered safer for immunocompromised individuals.