RESUMO
The prevalence and predictors of long COVID in young people remain unresolved. We aimed to determine the point prevalence of long COVID in non-hospitalised adolescents and young adults six months after the acute infection, to determine the risk of developing long COVID adjusted for possible confounders, and to explore a broad range of potential risk factors (prespecified outcomes). We conducted a prospective controlled cohort study of 404 SARS-CoV-2-positive and 105 SARS-CoV-2-negative non-hospitalised individuals aged 12–25 years (ClinicalTrial ID: NCT04686734). Data acquisition was completed February 2022. Assessments included pulmonary, cardiac and cognitive functional testing, biomarker analyses, and completion of a questionnaire, and were performed at inclusion (early convalescent stage) and six months follow-up. The WHO case definition of long COVID was applied. The point prevalence of long COVID at six months was 49% and 47% in the SARS-CoV-2-positive and negative group, respectively. SARS-CoV-2-positivity did not predict development of long COVID (relative risk 1.06, 95% CI 0.83 to 1.37). The main predictor was symptom severity at inclusion, which correlated strongly to personality traits. Low physical activity and loneliness were also predictive, while biological markers were not. In conlusion, our study aims were met, and the findings suggest that persistent symptoms were not driven by the infection, but were associated with psychosocial factors.
RESUMO
Background: The Omicron variant of SARS-CoV-2 is now overtaking the Delta variant in many countries. Results showing that sera from double vaccinated individuals have minimal neutralizing activity against Omicron may indicate that the higher rate of transmission is due to evasion from vaccine-induced immunity. However, there is little information about activation of recall responses to Omicron in vaccinated individuals. Methods: We measured inflammatory mediators, antibodies to the SARS-CoV-2 spike and nucleocapsid proteins, and spike peptide-induced release of interferon gamma in whole blood in 51 vaccinated individuals infected with Omicron, in 14 infected with Delta, and in 18 healthy controls. The median time points for the first and second samples were 7 and 14 days after symptom onset, respectively. Findings: Infection with Omicron or Delta led to a rapid and similar increase in antibodies to the SARS-CoV-2 spike and nucleocapsid proteins and spike peptide-induced interferon gamma in whole blood. Both the Omicron and the Delta infected patients had a mild and transient increase in inflammatory parameters. Interpretation: The results suggest that vaccine-induced immunological memory yields similar coverage for the Omicron and Delta variants.