A retrospective cohort of solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients will be assembled to determine the incidence of respiratory viral infections diagnosed during an inpatient admission in the first year post-transplant. A sub-cohort of patients that develop a respiratory viral infection within one year of transplantation will be leveraged to investigate factors associated with mortality in the three months after respiratory viral infection.

The purpose of the study is to 1) Determine the incidence of respiratory viral infections diagnosed during the first year post SOT and HSCT; 2a) Determine the all-cause mortality within 3 months of a respiratory viral infection diagnosed during an inpatient admission in the first year post SOT and HSCT; 2b) Determine the proportion of deaths within 3 months of a respiratory viral infection diagnosed during an inpatient admission deemed to be directly attributable to that infection; and 3) To identify factors known at time of onset of the inpatient respiratory viral infection that are associated with all-cause mortality. The study cohort will consist of any SOT or HSCT recipient ≤18 years of age that received their transplant between January 1st, 2010 and June 30th, 2013. Th cohort will determine the incidence of respiratory viral infections diagnosed during an inpatient admission in the first year post-transplant. A sub-cohort of patients that develop a respiratory viral infection within one year of transplantation will be leveraged to investigate factors associated with mortality in the 3 months after respiratory viral infection. Baseline and demographic characteristics will be summarized by standard descriptive summaries. Categorical variables will be summarized by frequencies while continuous variables will be summarized using mean, standard deviation and/or median, twenty-fifth and seventy-fifth percentiles, minimum, and maximum. This is a minimal risk study using data that will be collected retrospectively from medical charts. The only potential risk would be loss of confidentiality.

Inclusion Criteria:

• Males or females age 0 to <18 years at the time of HSCT or SOT
• Transplantation occurred between January 1st, 2010 and June 30th, 2013.

Exclusion Criteria:

• None

The study cohort will consist of any SOT or HSCT recipient ≤18 years of age that received their transplant between January 1st, 2010 and June 30th, 2013. Participants will have information collected from 30 days prior to transplant until the first of the following: 365 days post receipt of transplant, death, or loss to follow-up. If a patient has more than one viral respiratory infection of the same pathogen during the study period, then only the first infection will be considered unless isolated at least one month after the first positive test and only if after at least two negative tests for that same virus. A patient can contribute more than one viral respiratory infection if they are caused by different viral pathogens.