Almost one in four people infected with SARS-CoV-2 suffered from long-COVID, according to a population-based cohort study in Catalonia
23% of people infected with SARS-CoV-2 between 2021 and 2023 developed long-COVID, and more than half of them had symptoms that persisted for two years. Several factors increase the risk of developing long-COVID, such as being female and having a pre-existing chronic disease. These are the main findings of END-VOC researchers at ISGlobal and IGTP, Spain, who followed 2,764 adults from COVICAT, a population-based cohort designed to characterise the health impact of the pandemic on the population of Catalonia.
“A population-based cohort allowed us to better estimate the magnitude of long-COVID and identify risk and protective factors,” explains Manolis Kogevinas, ISGlobal researcher and lead author of the study. Participants completed three questionnaires — in 2020, 2021 and 2023 — and provided blood samples and medical records.
Risk factors
Being female, having experienced a severe COVID-19 infection and having a pre-existing chronic disease such as asthma were clear risk factors. People with obesity and high levels of IgG antibodies before vaccination were also more likely to develop long-COVID. In contrast, vaccination before infection and a healthy lifestyle were associated with a lower risk. The risk was also lower in people infected after the Omicron variant became dominant, which may be due to milder infections and/or greater overall immunity to the virus.
Three subtypes of long-COVID
Based on the symptoms reported by the participants and their medical records, the researchers identified three clinical subtypes of long-COVID. They were classified according to whether the symptoms were neurological and musculoskeletal, respiratory, or severe and involved multiple organs. In addition, the researchers found that 56% of people with long-COVID were still experiencing symptoms two years later.
“On the fifth anniversary of COVID-19, significant progress has been made in understanding the disease. However, as this study shows, the pandemic’s impact on mental health, work, and quality of life remains profound,” says Rafael de CID, scientific director of the GCAT cohort at IGTP.
Reference
Kogevinas, M., Karachaliou, M., Espinosa, A., Iraola-Guzmán, S., Castaño-Vinyals, G., Delgado-Ortiz, L., Farré, X., Blay, N., Pearce, N., Bosch de Basea, M., Alonso Nogués, E., Dobaño, C., Moncunill, G., de Cid, R., & Garcia-Aymerich, J. (March 2025). Risk, Determinants and Persistence of long-COVID in a Population-Based Cohort Study in Catalonia. BMC Medicine. http://doi.org/10.1186/s12916-025-03974-7
