Q. A 30-year-old man with a history of sickle cell anemia, status post-splenectomy in childhood, presents to your family practice clinic for a routine check-up. He is planning a trip to a region with a high risk of infectious diseases. As part of the pre-travel evaluation, you review his vaccination status. Which of the following vaccinations is most important to discuss and recommend for this patient due to his history of splenectomy?