Which of the following vaccine preventable illnesses is characterized by causing severe breathing problems?

Pneumonia is indeed characterized by severe breathing problems. It is an infection of the lungs that can lead to inflammation and fluid buildup, making it difficult for individuals to breathe properly. This condition can be particularly dangerous, especially for young children, the elderly, or those with weakened immune systems. Pneumonia can be caused by various pathogens, including bacteria, viruses, and fungi, and certain vaccines can help prevent specific types of pneumonia, notably the pneumococcal vaccines that protect against pneumococcal pneumonia.

The other illnesses mentioned, while they can have serious health implications, do not primarily or specifically cause severe breathing problems in the same way pneumonia does. Chickenpox, for instance, is primarily a skin rash and generally causes itchy blisters, while polio affects the nervous system and can lead to paralysis. Measles can lead to respiratory complications, but the defining characteristic of pneumonia remains its direct and significant impact on breathing.