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There has been an important change in the clinical characteristics and immune profile of Coronavirus disease 2019 (COVID‐19) patients during the pandemic thanks to the extensive vaccination programs. Here, we highlight recent studies on COVID‐19, from the clinical and immunological characteristics to the protective and risk factors for severity and mortality of COVID‐19. The efficacy of the COVID‐19 vaccines and potential allergic reactions after administration are also discussed. The occurrence of new variants of concerns such as Omicron BA.2, BA.4, and BA.5 and the global administration of COVID‐19 vaccines have changed the clinical scenario of COVID‐19. Multisystem inflammatory syndrome in children (MIS‐C) may cause severe and heterogeneous disease but with a lower mortality rate. Perturbations in immunity of T cells, B cells, and mast cells, as well as autoantibodies and metabolic reprogramming may contribute to the long‐term symptoms of COVID‐19. There is conflicting evidence about whether atopic diseases, such as allergic asthma and rhinitis, are associated with a lower susceptibility and better outcomes of COVID‐19. At the beginning of pandemic, the European Academy of Allergy and Clinical Immunology (EAACI) developed guidelines that provided timely information for the management of allergic diseases and preventive measures to reduce transmission in the allergic clinics. The global distribution of COVID‐19 vaccines and emerging severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants with reduced pathogenic potential dramatically decreased the morbidity, severity, and mortality of COVID‐19. Nevertheless, breakthrough infection remains a challenge for disease control. Hypersensitivity reactions (HSR) to COVID‐19 vaccines are low compared to other vaccines, and these were addressed in EAACI statements that provided indications for the management of allergic reactions, including anaphylaxis to COVID‐19 vaccines. We have gained a depth knowledge and experience in the over 2 years since the start of the pandemic, and yet a full eradication of SARS‐CoV‐2 is not on the horizon. Novel strategies are warranted to prevent severe disease in high‐risk groups, the development of MIS‐C and long COVID‐19. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: We develop an efficient visible‐light photoreodox‐catalyzed hydrodecarboxylation and deuterodecarboxylation of fatty acids for alkanes and deuterium alkanes. The key to the efficient transformation should attribute to the co‐catalysis of the suitable methoxy substituted acridine photocatalyst (Mes‐1,3,6,8‐tetramethoxy‐Acr‐3",5"‐dimethoxy‐Ph) and the hydrogen atom transfer catalyst 4′,4′‐dimethyl diphenyldisulfane, possibly via facilitating of quenching the active alkyl radicals to overcome the competitive homocoupling products, olefins via the disproportionation, cracking products via the C—C bond β‐scission. [ABSTRACT FROM AUTHOR]

The pandemic of coronavirus disease 2019 (COVID‐19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has caused an unprecedented global social and economic impact, and high numbers of deaths. Many risk factors have been identified in the progression of COVID‐19 into a severe and critical stage, including old age, male gender, underlying comorbidities such as hypertension, diabetes, obesity, chronic lung diseases, heart, liver and kidney diseases, tumors, clinically apparent immunodeficiencies, local immunodeficiencies, such as early type I interferon secretion capacity, and pregnancy. Possible complications include acute kidney injury, coagulation disorders, thoromboembolism. The development of lymphopenia and eosinopenia are laboratory indicators of COVID‐19. Laboratory parameters to monitor disease progression include lactate dehydrogenase, procalcitonin, high‐sensitivity C‐reactive protein, proinflammatory cytokines such as interleukin (IL)‐6, IL‐1β, Krebs von den Lungen‐6 (KL‐6), and ferritin. The development of a cytokine storm and extensive chest computed tomography imaging patterns are indicators of a severe disease. In addition, socioeconomic status, diet, lifestyle, geographical differences, ethnicity, exposed viral load, day of initiation of treatment, and quality of health care have been reported to influence individual outcomes. In this review, we highlight the scientific evidence on the risk factors of severity of COVID‐19. [ABSTRACT FROM AUTHOR]