Prevalence of long-term symptoms varies by using different post-COVID-19 definitions in positively and negatively tested adults: the PRIME post-COVID study

BackgroundLong-term symptoms after a SARS-CoV-2 infection (i.e., post-COVID-19 condition or long COVID), constitute a substantial public health problem. Yet, the prevalence remains currently unclear as different case definitions are used, and negatively tested controls are lacking. We aimed to estimate post-COVID-19 condition prevalence using six definitions. MethodsThe Prevalence, Risk factors, and Impact Evaluation (PRIME) post-COVID-19 condition study is a population-based sample of COVID-19 tested adults. End 2021, 61,655 adults were invited to complete an online questionnaire, including 44 symptoms plus a severity score (0-10) per symptom. The prevalence was calculated in both positively and negatively tested adults, stratified by time since their COVID-19 test (3-5, 6-11 or [≥]12 months ago). ResultsIn positives (n=7,405; 75.6%), the prevalence of long-term symptoms was between 26.9% and 64.1% using the six definitions, while in negatives (n=2,392; 24.4%) the prevalence varied between 11.4% and 32.5%. The prevalence of long-term symptoms potentially accountable to COVID-19 ranged from 17.9% to 26.3%. ConclusionThere is a (substantial) variation in prevalence estimates by using different definitions as is current practice, showing limited overlap between definitions, indicating that the essential post-COVID-19 condition criteria are still unclear. Including negatives is important to determine long-term symptoms accountable to COVID-19. Trial registration ClinicalTrials.gov Identifier: NCT05128695.