Prevalence and Clinical Characteristics of 15-Month Ambulatory Long COVID in Unvaccinated Adults

Background The extent of long COVID-19 across the world seems uncertain. Existing studies have not fully elucidated the profile, extent, and progression of the disease or its long-term severity. Objectives We described and analysed the symptoms and sequelae of unvaccinated patients with long COVID for up to 15 months in the Brazilian Amazon. Methods We interviewed 300 patients aged 18 years or older with post-COVID-19 symptoms, screened based on a confirmed diagnosis of COVID-19, from September 2020 to July 2021 in a cross-sectional study. Results The median age of the patients was 47 years, and 62% were women. Our data suggest that those who had mild COVID-19 (61%) in the acute phase of illness appeared to have prolonged symptoms of COVID-19; 84% had symptoms for more than 3 months that persisted for up to 15 months. Acute symptoms of COVID-19 that persisted over the long COVID were observed in 43% of patients; 14% developed new symptoms, and 43% had new and persistent symptoms. Less tolerable symptoms such as fatigue and shortness of breath were more common in male patients with non-mild illnesses, whereas more tolerable symptoms, such as anosmia and taste changes, were more common in female patients with mild illnesses. Conclusion Our results suggest a high prevalence of some symptoms related to the post-COVID-19 phase as well as a supposed correlation between the duration of COVID-19 and the number of symptoms, which appear to increase over time. These results can be explained by factors such as the pathophysiology of the disease itself; however, more comparative studies are needed to elucidate the role of other factors, such as environmental and socioeconomic factors.