Longitudinal sequelae of COVID-19 hospitalisation 3–12 months post Omicron infection

Persistent symptoms are frequently reported many months after SARS-CoV-2 infection. However, evidence of the association between long COVID features and initial Omicron infection severity is lacking. A prospective observational cohort study of n = 40 SARS-CoV-2 (Omicron B.1.1.529) infected individuals was performed, comprising n = 20 non-hospitalised and n = 20 hospitalised cases. ISARIC symptomology was recorded at baseline, 3-, 6- and 12-months post infection. Total and neutralising IgG antibody and inflammatory proteome concentrations were determined in plasma at baseline and 3 months. Pairwise comparisons were made between non-hospitalised and hospitalised subgroup biological and symptom data to investigate temporal changes. The non-hospitalised subgroup had higher median levels of Omicron variant specific ACE2 neutralising antibodies by 3 months, in particular females, though the difference was not statistically significant (BA.1 + R346K p = 0·06; BA.1 + L452R p = 0.08; BA.2 p = 0·09). Inflammatory proteins type 1 keratin, prostasin and leukocyte associated immunoglobulin receptor 1 were significantly elevated in hospitalised subgroup plasma 3 months post infection (padj < 0·05). Fatigue, muscle pain, headache, and cough symptoms subsided after 12 months in non-hospitalised, whilst significantly more hospitalised individuals reported continued muscle pain and shortness of breath (p < 0·05). This study provides the first evidence of the link between Omicron hospitalisation and long-term humoral immune response, inflammatory plasma proteome, and symptom persistence.