One Year after Mild COVID-19: The Majority of Patients Maintain Specific Immunity, But One in Four Still Suffer from Long-Term Symptoms

• Published in: Journal of clinical medicine Vol. 10; no. 15; p. 3305
• Main Authors: Rank, Andreas, Tzortzini, Athanasia, Kling, Elisabeth, Schmid, Christoph, Claus, Rainer, Löll, Eva, Burger, Roswitha, Römmele, Christoph, Dhillon, Christine, Müller, Katharina, Girl, Philipp, Hoffmann, Reinhard, Grützner, Stefanie, Dennehy, Kevin M.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 27.07.2021; MDPI
• Subjects: Antibodies; cellular immunity; Clinical medicine; Coronaviruses; COVID-19; COVID-19 vaccines; Cytokines; humoral immunity; Infections; Influenza; Peptides; persistent symptoms; Plasma; Questionnaires; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Viral infections; Viruses; United States > US; Germany
• ISSN: 2077-0383; 2077-0383
• DOI: 10.3390/jcm10153305

After COVID-19, some patients develop long-term symptoms. Whether such symptoms correlate with immune responses, and how long immunity persists, is not yet clear. This study focused on mild COVID-19 and investigated correlations of immunity with persistent symptoms and immune longevity. Persistent complications, including headache, concentration difficulties and loss of smell/taste, were reported by 51 of 83 (61%) participants and decreased over time to 28% one year after COVID-19. Specific IgA and IgG antibodies were detectable in 78% and 66% of participants, respectively, at a 12-month follow-up. Median antibody levels decreased by approximately 50% within the first 6 months but remained stable up to 12 months. Neutralizing antibodies could be found in 50% of participants; specific INFgamma-producing T-cells were present in two thirds one year after COVID-19. Activation-induced marker assays identified specific T-helper cells and central memory T-cells in 80% of participants at a 12-month follow-up. In correlative analyses, older age and a longer duration of the acute phase of COVID-19 were associated with higher humoral and T-cell responses. A weak correlation between long-term loss of taste/smell and low IgA levels was found at early time points. These data indicate a long-lasting immunological memory against SARS-CoV-2 after mild COVID-19.