HIV weakens the immune system, making individuals more susceptible to infections. Live attenuated vaccines, such as the MMR vaccine, contain a weakened form of the virus that could potentially cause harm to individuals with compromised immune systems. Therefore, it is not recommended to give the MMR vaccine to a 12-month-old baby with HIV.

The most appropriate action in this scenario would be to not give the vaccine. It is important to consult with a healthcare provider to discuss alternative vaccination options for the baby. Deferment of the immunization for 2 weeks may not be sufficient, as live attenuated vaccines should generally be avoided in HIV+ patients. Giving a half dose of the vaccine or administering paracetamol with future doses of the same vaccine are not appropriate actions in this case.

It is crucial to prioritize the health and safety of the baby with HIV by following the recommended guidelines for vaccination in individuals with compromised immune systems. Consulting with a healthcare provider who is knowledgeable about the specific needs of HIV+ patients is essential in making informed decisions regarding vaccination.