As the COVID-19 pandemic has progressed, long-COVID has emerged as a major problem that poses a significant challenge for attending physicians and health care policy makers. Therefore, we read with much interest the recently published unicentre study in the Journal of Infection by Righi et al.,1 carried out on 465 adult COVID-19 patients (235 [50.5%] hospital-admitted) followed-up during nine months, concluding that those with advanced age, intensive care unit (ICU) admission, and multiple symptoms at onset were more likely to have long-term COVID-19 symptoms, with negative impact on physical and mental wellbeing. Other studies have found that female gender, age, longer hospital stay, pre-existing hypertension, cardiovascular disease, diabetes, chronic obstructive pulmonary disease, smoking, obesity, and chronic alcoholism increase the likelihood of long-COVID.2,3 It is known that SARS-CoV-2 RNAemia is a predictor of COVID-19 severity and in-hospital complications.4,5 However, to the best of our knowledge, only two studies have assessed, up to one or three months after the acute COVID-19 onset, whether SARS-CoV-2 RNAemia may have an impact on long-COVID,6,7 both finding that RNAemia at presentation might predict the persistence of symptoms. However, these studies did not provide information regarding long-COVID symptoms nor the association with SARS-CoV-2 RNAemia beyond three months, and could not differentiate between “true” long-COVID and the convalescence phase of the SARS-CoV-2 infection.A.R. has received a predoctoral research grant from the Instituto de Salud Carlos III, Spanish Ministry of Science, Innovation and Universities, (PFIS grant FI18/00183). G.A.A. reports a predoctoral research grant from the 201808-10 project, funded by La Marató de TV3. This study was supported by the Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, the Spanish Network for Research in Infectious Diseases (REIPI, RD16/0016/0001, RD16/0016/0005, RD16/0016/0009, RD16/0016/0013)-co-financed by the European Development Regional Fund, A way to achieve Europe, Operative program Intelligent Growth 2014-2020, and the Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC) [CB21/13/00009; CB21/13/00006], Madrid, Spain. J.S.C. and E.C. received grants from the Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación, Proyectos de Investigación sobre el SARS-CoV-2 y la enfermedad COVID-19 (COV20/00580; COV20/00370). J.S.C. is a researcher belonging to the program “Nicolás Monardes” (C-0059–2018), Servicio Andaluz de Salud, Junta de Andalucía, Spain. Samples and data from patients included in this study from the Hospital Universitario Cruces (Bizkaia, Spain) were provided by the Basque Biobank (www.biobancovasco.org) and were processed following standard operation procedures with appropriate approval of the Ethical and Scientific Committees.Peer reviewe
