The Burden of Influenza and Rhinovirus among Hospitalized Adults Post the COVID-19 Pandemic

ABSTRACT

Background. Acute respiratory tract infections (ARIs) are a significant cause of morbidity in adults. Influenza is associated with about 490,600 hospitalizations and 34,200 deaths in the US in the 2018-2019 season. The burden of rhinovirus among adults hospitalized with ARI is less well known. We compared the burden of influenza and rhinovirus from 2 consecutive winter respiratory viral seasons in hospitalized adults and healthy controls pre-COVID-19 and one season mid-COVID-19 to determine the impact of rhinovirus as a pathogen. Methods. From Oct 2018 to Apr 2021, prospective surveillance of adults ≥50 years old admitted with ARI or COPD/CHF exacerbations at any age was conducted at two Atlanta hospitals. Adults were eligible if they lived within an eightcounty region around Atlanta and if their symptom duration was < 14 days. In the seasons from Oct 2018 to Mar 2020, asymptomatic adults ≥50 years old were enrolled as controls. Standard of care test results were included and those enrolled contributed nasopharyngeal swabs that were tested for respiratory pathogens using BioFire® FilmArray® Respiratory Viral Panel (RVP). Results. During the first two seasons, 1566 hospitalized adults were enrolled. Rhinovirus was detected in 7.5% (118) and influenza was detected in 7.7% (121). Rhinovirus was also detected in 2.2% of 466 healthy adult controls while influenza was detected in 0%. During Season 3, the peak of the COVID-19 pandemic, influenza declined to 0% of ARI hospitalizations. Rhinovirus also declined (p=0.01) but still accounted for 5.1% of all ARIs screened (Figure 1). Rhinovirus was detected at a greater rate in Season 3 than in asymptomatic controls in the first 2 seasons (p=0.008). In the first two seasons, Influenza was detected in 8.6% (24/276) of those admitted to the ICU. Rhinovirus was detected in 6.1% (17/276) of those admitted to the ICU but declined to 3.1% (8/258) in Season 3. Conclusion. Dramatic declines occurred in influenza in adults hospitalized with ARI, CHF, or COPD in Atlanta during the COVID-19 pandemic and with enhanced public health measures. Although rhinovirus declined during the COVID-19 pandemic, it continued to be identified at a rate higher than in historical controls. Additional data are needed to understand the role of rhinovirus in adult ARI, CHF, and COPD exacerbations.