We should get smart on some of the basics. The next 48 hours will be confusing.
(1) Pneumonia is not an infection, but rather an inflammation of the lungs. It is usually caused by an infection (viral/bacterial/fungal) but does not always have to be due to an infection.
(2) Pneumonia can affect one lung, or both. If it affects one lung, then you can almost function like normal.
(3) It can be contagious, but does not have to be. It just depends on what type of pneumonia you have (e.g. if the inflammation is caused by inhalation of toxic substances, then that is obviously not contagious), and the setting (e.g. if you have bacterial pneumonia, then that is more likely to be contagious for certain types of bacteria and if you are in a hospital where you are surrounded by individuals with a compromised immune system).
(4) An initial assessment of pneumonia may be incomplete (and inappropriate to release to the press) until several diagnostic tests are completed. As an example, if Hillary Clinton made an initial assessment on Friday, then she likely ordered a blood culture test to see if she has any bacteria in her bloodstream. A culture positive result is usually had in 1-3 days, but a culture negative result will take 5 days. If she is culture positive, then it takes an additional 24 hours to identify the specific pathogen. She has probably ordered a PCR test for some of the common viral forms, and those test take several hours. Regardless, the clinical diagnosis is not complete until the culture information comes in.