Hospital-Acquired Respiratory Viral Infections: Incidence, Morbidity, and Mortality in Pediatric and Adult Patients

Chow, Eric J.; Mermel, Leonard A.

Hospitalized patients with a positive result in one of these tests during the study period were identified using our institutional infection control software system (TheraDoc; Premier, Charlotte, NC). A definite nosocomial respiratory viral infection was defined as a patient whose number of days from hospital admission to symptom onset exceeded the upper range for the incubation period of the identified virus (Table 1) . A possible nosocomial respiratory viral infection case was defined as a patient in whom the number of days from hospital admission to symptom onset was within the range of the incubation period for the identified virus who were admitted without clinical signs or symptoms of a respiratory infection. A patient could be included more than once during the hospitalization if they had complete resolution of symptoms ascribed to the respiratory viral infection, recurrence of symptoms compatible with such an infection, and the time interval was greater than the above-noted incubation period. If the second such episode was due to a different virus, it was considered a definite case, and if it was due to the same virus, it was considered a possible case. Cases were assigned to a season based on the date when the symptoms of a respiratory viral infection were first documented in the medical record. Estimates of the incidence of nosocomial viral infections yearly in US acute care adult and pediatric hospitals were based on the number of such infections identified in the current study and the number of admissions to these hospitals during the 2014 fiscal reporting year based on data from the American Hospital Association.