New ORCHESTRA publication in Nature Communications: Latent transition analysis for longitudinal studies of post-acute infection syndromes

Earlier this month, the ORCHESTRA team published a new article in Nature Communications exploring data from ORCHESTRA longitudinal studies of Post-Acute COVID-19 , also known as Long COVID, with a novel trajectory-centric analysis method, Latent Transition Analysis (LTA). 

Long COVID is one of the Post-Infectious Sequelae (PAIS), which are defined as unexplained symptoms that appear after acute infection. Absence of a precise clinical case definition, and diverse and complex patients’ presentation complicate clinical research in this area, making comprehensive analysis particularly challenging. This recent study provides a generalisable framework for analysing longitudinal PAIS data using LTA, facilitating the identification of disease phenotypes and the patient-level analysis of transitions between them, without depending on predefined clinical categorisations. 

The dataset used was from the ORCHESTRA Long-Term Sequelae Cohort, comprising 5,094 patients from across Europe affected by SARS-CoV-2 infection. Data were collected the time of infection and from follow-up appointments at 6, 12, 18, and 24 months, aiming to investigate Long COVID. The LTA allows for investigation the clinical factors that change the variation of symptoms over time, without need of prior assumptions such as symptom profiles or progression paths. 

The model has been applied in Long COVID and identified distinct phenotypes, with patient trajectories influenced by age and sex, illustrating how LTA can enhance the interpretability of complex, time-resolved clinical data, enable personalised patient monitoring and management, and contribute to faster therapeutic development for other PAISs too. 

Moreover, this model shows how patients do not suffer additional symptoms once those are resolved. This resolution of symptoms can then impact the model of Long COVID management further down the patient care pathway. 

See the full article: https://www.nature.com/articles/s41467-026-68650-7  

Find out more about the ORCHESTRA project: https://www.id-care.net/projects/orchestra- 

The ORCHESTRA project, coordinated by Prof. Tacconelli and the ID-CARE team at the University of Verona, is funded by the European Union’s Horizon 2020 research and innovation programme and started on December 2020 with the aim of tackling the coronavirus pandemic. 

The project involves 37 partners from 15 countries, establishing an international large-scale-cohort to generate rigorous evidence in the field of prevention and treatment of SARS-CoV-2 infection. The identification of clinical and laboratory predictors to reduce severity and hospitalisation of COVID-19 and to prevent long COVID are among the main objectives of the project.