Although children and young adults appear to drive the spread of influenza virus and respiratory syncytial virus (RSV) in community settings, 1-3 this issue remains unclear. 4 We assessed the seasonality of respiratory viral infections with respect to age in 1 locale. Methods The study was approved by the Rhode Island Hospital institutional review board and was granted a waiver of informed consent because it involves the use of secondary data. This study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline. This cross-sectional case series involved detection of respiratory viruses among different age groups in Rhode Island. Data were derived from respiratory specimens sent to the Lifespan Microbiology Laboratory from inpatients and outpatients assessed at a Lifespan facility, which was licensed for 1165 beds and 757 380 outpatient visits in 2017, as well as patient specimens from other outpatient facilities throughout Rhode Island. All respiratory viruses positively identified in the laboratory by use of the respiratory viral panel and rapid influenza or RSV tests were reviewed. Adenovirus, coronavirus (not coronavirus disease 2019), influenza, parainfluenza, RSV, and human metapneumovirus were included for analysis. The weekly number of positive tests between January 2012 and December 2016 was extracted to construct a longitudinal case series for 4 age groups: 0 to 4 years, 5 to 17 years, 18 to 64 years, and 65 years and older. Analyses were performed using R Studio statistical software version 1.2.503 (R Project for Statistical Computing). Data analysis was performed from December 2018 to April 2019. Time series analysis and cross-correlation analysis were applied to determine the detection of respiratory viruses in the age group with the highest incidence and its correlation with detection in different age groups. Statistical significance was set at P < .05 and was calculated with linear regression and 2-sided Fisher exact tests. Results A total of 6733 respiratory viruses were detected and were predominantly detected in the following weeks: adenovirus, multiple peaks; coronavirus, weeks 50 to 7 (560 of 677 cases [83%]); influenza virus, weeks 50 to 9 (1487 of 1825 cases [84%]); parainfluenza virus, multiple weeks; RSV, weeks 48 to 11 (2198 of 2278 cases [97%]); and human metapneumovirus, weeks 1 to 17 (950 of 1017 cases [93%]) (Figure). With the exception of influenza virus, which first started in the 18-to 64-year age group, most respiratory virus infections occurred in the 0-to 4-year age group before other age groups, including peak detection of the coronavirus (Table). The Table shows the number and percentage of total cases, the lagged period (in weeks) with respect to the reference age group (ie, 0-4 years for adenovirus), and their mean (SE) correlation coefficients with statistical significance. In the 65 years and older age group, peak detection of influenza virus, parainfluenza virus, and human metapneumovirus occurred 3 weeks after peak detec...