To determine dynamic changes in clinical characteristics by examining an outbreak of adenovirus infection that occurred from December 20, 2012, to February 25, 2013, in Tianjin, China.

Active surveillance for febrile respiratory illnesses was conducted, and medical records of patients were collected. Real-time quantitative polymerase chain reaction and sequencing were used for pathogen identification and viral genome study, respectively. Student’s t-test was used to compare the mean values of normally distributed continuous variables. Mann-Whitney U or Kruskal-Wallis tests were used if continuous variables were not normally distributed. Pearson’s chi-square test or Fisher’s exact test was used to compare categorical variables.

The outbreak was sourced from the index case diagnosed as the common cold on December 20, 2012; a total of 856 cases were reported in the following 66 days. The pathogen was identified as human adenovirus (HAdV) 55. The symptoms manifested differently in severe and mild cases. Routine blood examinations, liver function indexes, and heart function indexes showed different dynamic patterns over time in hospitalized patients.

Clinical characteristics and laboratory examinations may reveal unique patterns over the course of HAdV-55 infection. (Disaster Med Public Health Preparedness. 2018;12:464–469)