The purpose of the study is to create a clinical pneumonia tool that can be used to predict the cause of community-acquired pneumonia, which is a lung infection that began outside of the hospital in critically ill children therefore limiting unnecessary antibiotic use. The investigators will enroll critically ill children admitted with acute respiratory failure and suspected pneumonia. Each patient will receive a clinical pneumonia score blinded from culture and respiratory viral panel results. All care after samples obtained will be at the discretion of the PICU team. The investigators believe that our clinical pneumonia scale with procalcitonin will accurately designate viral from bacterial etiologies.