Sputum and blood samples will be collected for measurement of IL-6 and IL-17 levels at time 0 in the ER or hospital, and then 5-7 days, 10-12 days, 33-35 days, and 56-58 days later. Specimens may be obtained from participants requiring mechanical ventilation during the first 24 hours of intubation only, and only if they are not suspected to have pneumonia.