Severe morbidity among hospitalised adults with acute influenza and other respiratory infections: 2014–2015 and 2015–2016

Abstract

Our objective was to identify predictors of severe acute respiratory infection in hospitalised patients and understand the impact of vaccination and neuraminidase inhibitor administration on severe influenza. We analysed data from a study evaluating influenza vaccine effectiveness in two Michigan hospitals during the 2014-2015 and 2015-2016 influenza seasons. Adults admitted to the hospital with an acute respiratory infection were eligible. Through patient interview and medical record review, we evaluated potential risk factors for severe disease, defined as ICU admission, 30-day readmission, and hospital length of stay (LOS). Two hundred sixteen of 1119 participants had PCR-confirmed influenza. Frailty score, Charlson score and tertile of prior-year healthcare visits were associated with LOS. Charlson score >2 (OR 1.5 (1.0-2.3)) was associated with ICU admission. Highest tertile of prior-year visits (OR 0.3 (0.2-0.7)) was associated with decreased ICU admission. Increasing tertile of visits (OR 1.5 (1.2-1.8)) was associated with 30-day readmission. Frailty and prior-year healthcare visits were associated with 30-day readmission among influenza-positive participants. Neuraminidase inhibitors were associated with decreased LOS among vaccinated participants with influenza A (HR 1.6 (1.0-2.4)). Overall, frailty and lack of prior-year healthcare visits were predictors of disease severity. Neuraminidase inhibitors were associated with reduced severity among vaccine recipients.

Risk-factors for re-admission and outcome of patients hospitalized with confirmed COVID-19

“…Our results are similar to those reported by Lavery et al, however they reported on same-hospital re-admission 5 . These rates are also similar to those reported for patients hospitalized with acute respiratory illness secondary to seasonal influenza virus, patients hospitalized with community acquired pneumonia, or patients hospitalized in medical and geriatric wards 21 , 24 – 27 . They are lower than reported for patients hospitalized because of exacerbation of chronic pulmonary disease or congestive heart failure 25 .…”

“…Hypertension and malignancy were also more common in re-admitted non-severe patients with COVID-19 12 . These variables were also described as risk factors for re-admission among medical and geriatric patients, patients with seasonal influenza of community acquired pneumonia 20 , 21 , 24 , 26 , 27 .…”

Clinical outcomes and characteristics of patients hospitalized for Influenza or COVID-19 in Germany

“…Interestingly, a slightly larger proportion of patients with Influenza have underlying comorbidities such as hypertension, diabetes, or COPD. In previous studies, these factors have been associated with a complicated course of Influenza infection ( Lina et al, 2020 , Schanzer et al, 2008 , Segaloff et al, 2018 ). In accordance, the reported comorbidities are similarly frequent in patients with COVID-19 with severe disease progression, increase with advanced age, and might be associated with a poor outcome ( Aggarwal et al, 2020 , Brück, 2020 , Richardson et al, 2020 , Zhou et al, 2020 ).…”

Antibody and Cell-Mediated Immune Responses Are Correlates of Protection against Influenza Infection in Vaccinated Older Adults

“…Considering the high number of participants required to power vaccine efficacy trials that are based on LCII and LCII-related outcomes, many have argued that accurate immunological correlates of protection should be given consideration as an alternative primary outcome, at least in the early phases of vaccine development [ 7 ]. This approach is especially practical for important subgroups of the population, such as older adults living with frailty and/or chronic conditions, who are at an increased risk of influenza hospitalization [ 8 ] and severity of related outcomes [ 9 ], regardless of vaccination status [ 10 ]. That being said, few correlates have been validated in older adults, and those that have are based primarily on hemagglutination inhibition antibody responses [ 11 , 12 ], which do not provide appreciable cross-strain immunity within the subtypes of influenza.…”