Persistent Variability in Long COVID Definitions

A standardised, validated definition of Long COVID is still absent from scientific studies. A study published in the medical journal JAMA Network Open reveals that the prevalence of Long COVID depends on how the condition is defined in published literature.   

For their investigation, the researchers used data of more than 4,500 adults from the INSPIRE registry. This registry enrolled adults who experienced acute illness with symptoms consistent with COVID-19 between December 2020 and August 2022. All individuals were tested for SARS-CoV-2 coronavirus and followed up for several months afterwards. 

The study applied 5 different published definitions of Long COVID to the same individuals on the INSPIRE Registry who had tested positive for SARS-CoV-2. The definitions vary with respect to the number, duration and type of the symptoms needed for a Long COVID diagnosis. The prevalence rates of Long COVID diagnoses varied accordingly. Depending on the definition used, between 31 and 42 per cent of participants were diagnosed with Long COVID at 3 months. At 6 months, rates varied between 15 and 22 per cent depending on the definition used. 

The study revealed that disparate definitions directly affect Long COVID prevalence estimates. This hinders not only the comparability of studies, but also the targeted identification and treatment of those affected. Therefore, the authors of the study are calling for standardised, clearly defined criteria for Long COVID