Characterising long COVID: a living systematic review.

BACKGROUND: While it is now apparent clinical sequelae (long COVID) may persist after acute COVID-19, their nature, frequency and aetiology are poorly characterised. This study aims to regularly synthesise evidence on long COVID characteristics, to help inform clinical management, rehabilitation strategies and interventional studies to improve long-term outcomes. METHODS: A living systematic review. Medline, CINAHL (EBSCO), Global Health (Ovid), WHO Global Research on COVID-19 database, LitCovid and Google Scholar were searched till 17 March 2021. Studies including at least 100 people with confirmed or clinically suspected COVID-19 at 12 weeks or more post onset were included. Risk of bias was assessed using the tool produced by Hoy et al. Results were analysed using descriptive statistics and meta-analyses to estimate prevalence. RESULTS: A total of 39 studies were included: 32 cohort, 6 cross-sectional and 1 case-control. Most showed high or moderate risk of bias. None were set in low-income countries and few included children. Studies reported on 10 951 people (48% female) in 12 countries. Most included previously hospitalised people (78%, 8520/10 951). The longest mean follow-up time was 221.7 (SD: 10.9) days post COVID-19 onset. Over 60 physical and psychological signs and symptoms with wide prevalence were reported, most commonly weakness (41%; 95% CI 25% to 59%), general malaise (33%; 95% CI 15% to 57%), fatigue (31%; 95% CI 24% to 39%), concentration impairment (26%; 95% CI 21% to 32%) and breathlessness (25%; 95% CI 18% to 34%). 37% (95% CI 18% to 60%) of patients reported reduced quality of life; 26% (10/39) of studies presented evidence of reduced pulmonary function. CONCLUSION: Long COVID is a complex condition with prolonged heterogeneous symptoms. The nature of studies precludes a precise case definition or risk evaluation. There is an urgent need for prospective, robust, standardised, controlled studies into aetiology, risk factors and biomarkers to characterise long COVID in different at-risk populations and settings. PROSPERO REGISTRATION NUMBER: CRD42020211131.

What are the long-term symptoms and complications of COVID-19: a protocol for a living systematic review.

Although the majority of patients with COVID-19 will experience mild to moderate symptoms and will recover fully, there is now increasing evidence that a significant proportion will experience persistent symptoms for weeks or months after the acute phase of the illness. These symptoms include, among others, fatigue, problems in breathing, lack of smell and taste, headaches, and also depression and anxiety. It has also become clear that the virus has lasting effects not only on the respiratory system but also on other parts of the body, including the heart, liver, and the nervous system. In this paper we present a protocol for a living systematic review that aims to synthesize the evidence on the prevalence and duration of symptoms and clinical features of post-acute COVID-19 and its long-term complications. The living systematic review will be updated regularly, initially monthly with update cycles under continuous review as the pace of new evidence generated develops through the pandemic. We will include studies that follow up with COVID-19 patients who have experienced persistent mild, moderate or severe symptoms, with no restrictions regarding country, setting, or language. We will use descriptive statistics to analyse the data and our findings will be presented as infographics to facilitate transcription to lay audiences. Ultimately, we aim to support the work of policy makers, practitioners, and patients when planning rehabilitation for those recovering from COVID-19. The protocol has been registered with PROSPERO ( CRD42020211131, 25/09/2020).