Long-term complications after infection with SARS-CoV-1, influenza and MERS-CoV - Lessons to learn in long COVID?

The COVID-19 pandemic has affected millions of people worldwide, and while the mortality rate remains the primary concern, it is becoming increasingly apparent that many COVID-19 survivors experience long-term sequelae, representing a major concern for both themselves and healthcare providers. Comparing long-term sequelae following COVID-19 to those of other respiratory viruses such as influenza, MERS-CoV, and SARS-CoV-1 is an essential step toward understanding the extent and impact of these sequelae. A literature search was carried out using the PubMed. database. Search-terms included "persistent", "long-term", "chronic", and MeSH-terms for SARS-CoV-1, MERS-CoV and Influenza. Only English-language articles were selected. Articles were screened by title/abstract and full-text readings. Key points for comparison were persistent symptoms > 4 weeks, virus type, study design, population size, admission status, methods, and findings. Thirty-one articles were included: 19 on SARS-CoV-1, 10 on influenza, and 2 on MERS-CoV-survivors. Damage to the respiratory system was the main long-term manifestation after the acute phase of infection. Quality of life-related and psychological sequelae were the second and third most widely reported symptoms, respectively. Consistent with long-term sequelae from COVID-19, persisting cardiovascular, neurological, musculoskeletal, gastrointestinal impairments were also reported. In summary, the long-term sequelae following COVID-19 are a significant concern, and while long-term sequelae following influenza, MERS-CoV, and SARS-CoV-1 have also been reported, their prevalence and severity are less clear. It is essential to continue to study and monitor the long-term effects of all respiratory viruses so as to improve our understanding and develop strategies for prevention and treatment.

Identification and Characterization of a Nationwide Danish Adult Common Variable Immunodeficiency Cohort.

In this study, we identified all adults living in Denmark diagnosed with common variable immunodeficiency (CVID) and characterized them according to clinical presentation and EUROclass classification. Using a retrospective, cross-sectional design, possible CVID patients were identified in the Danish National Patient Register and Centers in Denmark treating patients with primary immunodeficiencies. The CVID diagnosis was verified by review of medical records. One-hundred-seventy-nine adults with CVID were identified. This corresponds to a prevalence of 1:26,000. The median age at onset of symptoms was 29 years with no sex difference. The median age at diagnosis was 40 years. Males were diagnosed earlier with a peak in the fourth decade of life, whereas females were diagnosed later with a peak in the sixth decade. The median diagnostic delay was seven years. Recurrent sinopulmonary infections were seen in 92.7% of the patients. The prevalence of non-infectious complications was similar to that of previously reported cohorts: bronchiectasis (35.8%), splenomegaly (22.4%), lymphadenopathy (26.3%), granulomatous inflammation (3.9%) and idiopathic thrombocytopenic purpura (14.5%). Non-infectious complications were strongly associated with B cell phenotype, with all having a reduced number of isotype-switched memory B cells. One-hundred-seventy (95%) were treated with immunoglobulin replacement therapy, primarily administered subcutaneously. According to international guidelines, diagnostic evaluation was inadequate in most cases. This study emphasizes the need for improved diagnostic criteria and more awareness of CVID as a differential diagnosis. Diagnosis and management of CVID patients is a challenge requiring specialists with experience in the field of PID.