**Question:** After splenectomy which vaccine has to be given?

**Core Concept:** Splenectomy is a surgical procedure to remove the spleen, which plays a crucial role in immune system function. Post-splenectomy, patients are at increased risk of infections due to impaired immune response. Vaccination is essential to prevent serious complications from encapsulated pathogens like Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis.

**Why the Correct Answer is Right:** After splenectomy, the patient's immune system is weakened, making them susceptible to infections. The polysaccharide vaccines (Pneumococcal, Haemophilus influenzae, and Neisseria meningitidis) are recommended to protect against these encapsulated pathogens. These vaccines work by stimulating the production of antibodies against specific polysaccharide antigens, which are not affected by the splenectomy-induced immune dysfunction.

**Why Each Wrong Option is Incorrect:**

A. Polio vaccine: This vaccine primarily targets poliovirus and is less affected by splenectomy-induced immune dysfunction.
B. Measles, mumps, and rubella (MMR) vaccine: The MMR vaccine targets viruses (measles, mumps, and rubella) and is also less affected by splenectomy.
C. Inactivated polio vaccine (IPV): IPV is a similar vaccine to the oral polio vaccine (OPV), which is less affected by splenectomy.
D. Pneumococcal polysaccharide vaccine: This vaccine targets Streptococcus pneumoniae, which is the bacterium causing pneumococcal infections, and is less affected by splenectomy.

**Correct Answer:** D. Pneumococcal polysaccharide vaccine

**Clinical Pearl:** Post-splenectomy patients should be vaccinated against encapsulated bacteria to reduce the risk of severe infections. The immune system's inability to clear these bacteria can lead to life-threatening complications. Vaccination remains crucial even for those who have undergone splenectomy due to other reasons like trauma or autoimmune diseases.