di , 26/05/2023

The COVID-19 pandemic has undoubtedly posed significant challenges to global healthcare systems. However, it has also spurred unprecedented scientific research and technological advancements, enabling a better understanding of the novel coronavirus, SARS-CoV-2. One crucial aspect of this understanding has been the study of self-reported symptoms, which has not only aided in monitoring the long-term effects of COVID-19 outside of hospital settings but also facilitated personalized patient care. In a groundbreaking study summarized in The Lancet Digital Health, researchers sought to delve into the diverse profiles of post-COVID-19 condition, considering viral variants and vaccination status as key factors.

The Evolving Symptoms and Variants

Since the first reported cases in December 2019, SARS-CoV-2 has infected millions of people worldwide, causing varying symptoms and outcomes. The symptoms of COVID-19 have evolved as new viral variants emerged, leading to changes in the clinical presentation and severity. Survivors of COVID-19 often report persistent symptoms that continue to affect their quality of life even after the acute illness phase. Notably, the prevalence and nature of these long-term symptoms have been found to differ across SARS-CoV-2 variants.

Study Design and Methodology

The prospective longitudinal cohort study analyzed data from UK-based adults, aged 18-100 years, who regularly reported their health status through the Covid Symptom Study smartphone app. The study included participants who tested positive for SARS-CoV-2 after being physically normal for at least 30 days. The researchers focused on individuals who developed symptoms lasting longer than 28 days from the initial positive test, defining this as long COVID. Additionally, they examined post-COVID-19 condition, which involved symptoms persisting for at least 84 days after the initial positive test. By employing unsupervised clustering analysis of time-series data, the researchers aimed to identify distinct symptom profiles for vaccinated and unvaccinated individuals across various SARS-CoV-2 variants.

Findings and Implications

The study included a total of 9,804 individuals with long COVID, of whom 15% developed a post-COVID-19 condition. The researchers identified different symptom profiles within and across variants. The wild-type variant (in unvaccinated people) showed four distinct endotypes. Alpha variant (in unvaccinated people) showed seven endotypes, while the vaccinated delta variant group exhibited five endotypes. Across all variants, researchers identified three main clusters of symptoms: cardiorespiratory, central neurological, and multi-organ systemic inflammatory. Gastrointestinal symptoms showed a less diverse clustering pattern across viral variants.

The findings shed light on the heterogeneous nature of post-COVID-19 condition, characterized by varying combinations of symptoms, durations, and functional outcomes.

This classification holds immense potential in enhancing our understanding of the different mechanisms underlying post-COVID-19 conditions, as well as identifying subgroups of individuals at risk of prolonged debilitation. Such insights are invaluable for tailoring personalized care and developing targeted interventions for affected individuals.


The rapid evolution and spread of SARS-CoV-2 have necessitated extensive research to comprehend its impact on human health. This study’s innovative approach, analyzing self-reported symptoms and leveraging clustering analysis, has contributed significantly to unraveling the diverse profiles of post-COVID-19 condition based on viral variants and vaccination status. By understanding the distinct characteristics of this condition, healthcare professionals can provide tailored care to individuals experiencing prolonged symptoms, thereby enhancing their well-being and recovery.

Funding for this study was provided by various organizations, including the UK Government Department of Health and Social Care, Wellcome Trust, and National Institute for Health Research, among others.