Which of the following patients would be a candidate for PPSV23?

The 25-year-old man who smokes cigarettes is a candidate for pneumococcal polysaccharide vaccine (PPSV23) because smoking is an important risk factor for pneumococcal disease. The Centers for Disease Control and Prevention (CDC) recommends PPSV23 for adults aged 19 years or older who smoke or have asthma, as these individuals are at increased risk of developing serious pneumonia and invasive pneumococcal disease.

Vaccination against pneumococcus using PPSV23 is particularly significant for individuals with certain risk factors, including tobacco use. In this case, the young man's smoking status makes him eligible for this vaccination, thereby helping to protect him against potential respiratory infections that could lead to more severe health complications.

The other candidates described do not meet the criteria for PPSV23 vaccination. For instance, the 12-month-old boy with asthma would typically receive the pneumococcal conjugate vaccine (PCV13) instead, as pneumococcal vaccination guidelines emphasize the importance of PCV13 in infants and children. The pregnant woman is also not indicated for this vaccine during pregnancy unless she has an additional risk factor or a specific health condition. Lastly, the 50-year-old woman with no medical conditions wouldn't qualify for PPS