Upper Respiratory Symptoms as Long COVID: Insight from a Multicenter Cohort Study

This study aimed to investigate the clinical features of long COVID cases presenting with upper respiratory symptoms, a topic not yet fully elucidated.

Prospective cohort study.

A multicenter study involving 26 medical facilities in Japan.

Inclusion criteria were patients aged ≥18 years old with a confirmed COVID-19 diagnosis via severe acute respiratory syndrome coronavirus 2 polymerase chain reaction or antigen testing, who were hospitalized at the participating medical facilities. Analyzing clinical information and patient-reported outcomes from 1009 patients were analyzed. The outcome measured the degree of initial symptoms for taste or olfactory disorders and assessed the likelihood of these symptoms persisting as long COVID, as well as the impact on quality of life if the upper respiratory symptoms persisted as long COVID.

Patients with high albumin, low C-reactive protein, and low lactate dehydrogenase in laboratory tests tended to experience taste or olfactory disorders as part of long COVID. Those with severe initial symptoms had a higher risk of experiencing residual symptoms at 3 months, with an odds ratio of 2.933 (95% confidence interval [CI], 1.282-6.526) for taste disorders and 3.534 (95% CI, 1.382-9.009) for olfactory disorders. Presence of upper respiratory symptoms consistently resulted in lower quality of life scores.

The findings from this cohort study suggest that severe taste or olfactory disorders as early COVID-19 symptoms correlate with an increased likelihood of persistent symptoms in those disorders as long COVID.