COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Prognosis Michelen M, Manoharan L, Elkheir N, et al. Characterising long COVID: a living systematic review. BMJ Glob Health. 2021 Sep;6(9). pii: bmjgh-2021-005427. doi: 10.1136/bmjgh-2021-005427.

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.


Discipline / Specialty Area Score
Infectious Disease
Pediatrics (General)
Family Medicine (FM)/General Practice (GP)
General Internal Medicine-Primary Care(US)
Hospital Doctor/Hospitalists
Internal Medicine
Pediatric Hospital Medicine
Pediatric Neonatology
Comments from MORE raters

Family Medicine (FM)/General Practice (GP) rater

This is an important step in beginning to understand long COVID. The evidence presented here is two fold: reporting the symptoms attributed to long COVID across studies; and the lack of understanding of this disease. The constellations of symptoms is heterogeneous and often-nonspecific; we need much careful research to tease out the precise mechanisms and diagnosis.

Family Medicine (FM)/General Practice (GP) rater

The story is unfolding and this SR provides additonal information on long Covid. It is good that the review will be regularly updated. It would be good to see the effect of vaccination on long covid symptoms included in the next iteration.

Infectious Disease rater

This is one of the most professional communications on an extremely significant subject; long covid is poised to become a future pandemic of its own.

Internal Medicine rater

The generalizability is impaired because it din't include studies from low-income countries.

Pediatric Neonatology rater

Early call to provide precise standardized outcomes and symptoms for Covid long haul.

Pediatrics (General) rater

As a neonatologist, I find this article could help in recognizing that the clinical spectrum of long COVID is limited and based on heterogenous data. So, this might help in following neonates with COVID-19.