Post-COVID-19 symptoms 6 months after acute infection among hospitalized and non-hospitalized patients

To assess the prevalence of and factors associated with post-coronavirus disease 2019 (COVID-19) syndrome 6 months after the onset. A bidirectional prospective study. Interviews investigated symptoms potentially associated with COVID-19 6 months after the disease onset of all consecutive adult inpatients and outpatients with COVID-19 attending Udine Hospital (Italy) from March to May 2020. IgG antibodies against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) were also evaluated 6 months after the onset of symptoms, at the time of the interview. A total of 599 individuals were included (320 female, 53.4%; mean age 53 years, SD 15.8) and interviewed 187 days (22 SD) after onset. The prevalence of post-COVID-19 syndrome was 40.2% (241/599). The presence of IgG antibodies was significantly associated with the occurrence of post-COVID-19 syndrome (OR 2.56, 95% CI 1.48–4.38, p 0.001) and median SARS-CoV-2 IgG titres were significantly higher in patients with post-COVID-19 syndrome than in patients without symptoms (42.1, IQR 17.1–78.4 vs. 29.1, IQR 12.1–54.2 kAU/L, p 0.004). Female gender (OR 1.55, 95% CI 1.05–2.27), a proportional increase in the number of symptoms at the onset of COVID-19 (OR 1.81, 95% CI 1.59–2.05) and ICU admission OR 3.10, 95% CI 1.18–8.11) were all independent risk factors for post-COVID-19 syndrome. The same predictors also emerged in a subgroup of 231 patients with the serological follow-up available at the time of the interview alongside the proportional increase in anti-SARS-CoV-2 IgG (OR 1.01, 95% CI 1.00–1.02, p 0.04). Prospective follow-up could be offered to specific subgroups of COVID-10 patients, to identify typical symptoms and persistently high anti-SARS-CoV-2 IgG titres as a means of early detection of post-COVID-19 long-term sequelae.