Does everyone with pneumonia get a cough? No. In fact, people over 65 often have neither a cough nor fever, helping their lung infection to stay under the radar. Experts say a key sign of pneumonia in this age group (and sometimes the only sign) is a sudden change in mental awareness. How can you tell if an infant has pneumonia? Babies may have less-typical symptoms of pneumonia. They may vomit or appear restless or listless, with low energy. They may also grunt, have a bluish tone to their skin and lips, or have difficulty eating. Any of these are good reasons to call your pediatrician.