Methods

Children’s Hospital Colorado (CHCO) is a large academic quaternary care center serving children in Colorado and the seven surrounding states. The main hospital campuses in Aurora and Colorado Springs have 575 beds and admit over 15,000 inpatients per year. For more than twenty years prior to the COVID-19 pandemic, seasonal visitation restrictions were utilized to prevent HA-RVI at CHCO. This is common practice in both adult and pediatric institutions. Restrictions were implemented annually from December 1^st to April 30^th when historically there has been elevated institutional and community incidence of respiratory viruses. No visitors under the age of 13 were permitted, but the number of visitors was not restricted. Visitor illness screening occurred year-round and was performed by trained screeners. No ill visitors were permitted to visit unless they were legally authorized representatives (LARs). LARs were initially asked to go home until well. If ill LARs insisted on visiting, guidance for performing hand hygiene was provided and LARs with respiratory viral symptoms were asked to wear a mask. Visitor illness screening remained the same during all periods of this study. During the COVID-19 pandemic, our hospitals implemented enhanced infection prevention measures: restricting visitation to 2 LARs, performing visitor illness and COVID-19 exposure screening at entry into the hospital, and requiring universal masking for all visitors and team members in all areas of the hospital except for LARs in a patient room when no team members were present. These restrictions were implemented in April 2020 and maintained until June 2022 when COVID-19 was at regionally low rates. At that time, a year-round ten-person LAR approved visitor list was implemented. The list was inclusive of LARs and siblings of any age. Non-sibling visitors under the age of 18 years were not permitted. Mandatory universal masking was continued for all visitors and team members until April 2023, when masking became voluntary.

A HA-RVI was defined as any hospitalized patient with a positive respiratory virus test that was collected after the average incubation period for that respiratory virus.^{Reference Kimberlin, Brady, Jackson and Long5} A positive test at admission or during the incubation period post admission was considered community acquired. Monthly HA-RVI rates were calculated as the number of HA-RVI per 10,000 patient days. HA-RVI rates from four periods were compared: (1) pre-COVID (December 2017–March 2020) during respiratory viral seasons (December 1^st–April 30^th), (2) during initial COVID restrictions encompassing universal masking and 2 LAR visitors (May 2020–May 2022), (3) during continued universal masking but relaxation of visitor restrictions using the ten person visitor list (June 2022–March 2023), and (4) discontinuation of mandatory masking but continued use of the ten person visitor list (April 2023–April 2024) (Table 1).

Table 1.

Visitation practices by period.

U charts examining counts of HA-RVI per 10,000 patient days were constructed. An ANOVA was performed to compare the means across time periods to determine if at least one mean was different (P <.001). In the pre-COVID period, only months during the respiratory season were included for comparison purposes. There was a one-month period when the first intervention was started that was not included in the U chart calculations, which allowed for intervention start-up. A sensitivity analysis that included all months, an interrupted time series analysis, and a changepoint identification analysis were performed (see supplemental material). Means were then compared between the four groups using a one-way analysis of variance (ANOVA) test. Since the ANOVA was significant at the P <.05 level, two group-comparisons were used to identify where differences existed after adjustment for multiple comparisons using Tukey’s honestly significant test. All statistical tests were two-sided and P < .05 was considered statistically significant. Statistical analyses were performed in SAS 9.4 ^©2020 by SAS Institute Inc., Cary, NC, USA, U charts were developed using SPC for Excel version 6, or R-RStudio2024.12.0 Build 467 © 2009–2024 Posit Software, PBC.