We aimed to investigate changes in pulmonary function and computed tomography (CT) findings in patients with coronavirus disease 2019 (COVID-19) during the recovery period. COVID-19 patients underwent symptom assessment, pulmonary function tests, and high-resolution chest CT 6 months after discharge from the hospital. Of the 54 patients enrolled, 31 and 23 were in the moderate and severe group, respectively. The main symptoms 6 months after discharge were fatigue and exertional dyspnea, experienced by 24.1% and 18.5% of patients, respectively, followed by smell and taste dysfunction (9.3%) and cough (5.6%). One patient dropped out of the pulmonary function tests. Of the remaining 54 patients, 41.5% had pulmonary dysfunction. Specifically, 7.5% presented with restrictive ventilatory dysfunction (forced vital capacity <80% of the predicted value), 18.9% presented with small airway dysfunction, and 32.1% presented with pulmonary diffusion impairment (diffusing capacity for carbon monoxide <80% of the predicted value). Of the 54 patients enrolled, six patients dropped out of the chest CT tests. Eleven of the remaining 48 patients presented with abnormal lung CT findings 6 months after discharge. Patients with residual lung lesions were more common in the severe group (52.6%) than in the moderate group (3.4%); a higher proportion of patients had involvement of both lungs (42.1% vs. 3.4%) in the severe group. The residual lung lesions were mainly ground-glass opacities (20.8%) and linear opacities (14.6%). Semiquantitative visual scoring of the CT findings revealed significantly higher scores in the left, right, and both lungs in the severe group than in the moderate group. COVID-19 patients 6 months after discharge mostly presented with fatigue and exertional dyspnea, and their pulmonary dysfunction was mostly characterized by pulmonary diffusion impairment. As revealed by chest CT, the severe group had a higher prevalence of residual lesions than the moderate group, and the residual lesions mostly manifested as ground-glass opacities and linear opacities.

The SARS-CoV-2 Omicron variant evades most currently approved neutralizing antibodies (nAbs) and caused drastic decrease of plasma neutralizing activity elicited by vaccination or prior infection, urging the need for the development of pan-variant antivirals. Breakthrough infection induces a hybrid immunological response with potentially broad, potent and durable protection against variants, therefore, convalescent plasma from breakthrough infection may provide a broadened repertoire for identifying elite nAbs. We performed single-cell RNA sequencing (scRNA-seq) and BCR sequencing (scBCR-seq) of B cells from BA.1 breakthrough-infected patients who received 2 or 3 previous doses of inactivated vaccine. Elite nAbs, mainly derived from the IGHV2–5 and IGHV3-66/53 germlines, showed potent neutralizing activity across Wuhan-Hu-1, Delta, Omicron sublineages BA.1 and BA.2 at picomolar NT₅₀ values. Cryo-EM analysis revealed diverse modes of spike recognition and guides the design of cocktail therapy. A single injection of paired antibodies cocktail provided potent protection in the K18-hACE2 transgenic female mouse model of SARS-CoV-2 infection.

Omicron variants of SARS-CoV-2 have spread rapidly worldwide; however, most infected patients have mild or no symptoms. This study aimed to understand the host response to Omicron infections by performing metabolomic profiling of plasma. We observed that Omicron infections triggered an inflammatory response and innate immune, and adaptive immunity was suppressed, including reduced T-cell response and immunoglobulin antibody production. Similar to the original SARS-CoV-2 strain circulating in 2019, the host developed an anti-inflammatory response and accelerated energy metabolism in response to Omicron infection. However, differential regulation of macrophage polarization and reduced neutrophil function has been observed in Omicron infections. Interferon-induced antiviral immunity was not as strong in Omicron infections as in the original SARS-CoV-2 infections. The host response to Omicron infections increased antioxidant capacity and liver detoxification more than in the original strain. Hence, these findings suggest that Omicron infections cause weaker inflammatory alterations and immune responses than the original SARS-CoV-2 strain.

The aim of this study was to evaluate the respiratory and physical function of patients who retested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA during post-coronavirus disease 2019 (COVID-19) rehabilitation. A total of 302 discharged COVID-19 patients were included. Discharged patients were followed up for 14 days to 6 months. The modified Medical Research Council (mMRC) dyspnea scale, Borg rating of perceived exertion, and manual muscle testing (MMT) scores on day 14 and at 6 months after discharge were compared between the redetectable positive (RP) and non-RP (NRP) groups. Prognoses of respiratory and physical function were compared between patients who recovered from moderate and severe COVID-19. Of the study patients, 7.6% were RP. The proportion of patients who used antiviral drugs was significantly lower in the RP group than in the NRP group. There were no differences in mMRC, Borg, or MMT scores within the RP and NRP groups. The mMRC, Borg, and MMT scores were worse for patients with severe disease when compared to those with moderate disease at both follow-up time points. COVID-19 patients who did not take antiviral drugs were more likely to be RP after discharge. The recovery of respiratory and physical function was not related to re-positivity during rehabilitation, but was related to disease severity during hospitalization.

The coronavirus disease 2019 (COVID-19) pandemic is straining global health resources, and the prevalence of severe disease appears to vary across countries. In accordance with PRISMA guidelines, we performed a systematic review and meta-analysis of clinical features and underlying medical conditions of COVID-19. Eighty-seven studies, involving 1,434,931 COVID-19 patients from the Americas, Asia, Europe, and Oceania, were included. Geographically, the rate of severity was highest in Asia (95% confidence interval (CI) 0.23‒0.30). The rates of comorbidities of COVID-19 patients in the Americas were significantly higher than those in Asia. Most Asian patients had fever (95%CI 0.70‒0.81), and most Oceanian patients had cough (95%CI 0.68‒0.70) as their prevalent symptom. Dyspnea was common in the Americas (95%CI 0.33‒0.64), Europe (95%CI 0.29‒0.64), and high latitude regions (95%CI 0.53‒0.82). European patients exhibited significantly high rates of loss of smell and taste (95%CI 0.60–0.97). In low-latitude regions, cancer (95%CI 14.50‒4.89) had the strongest correlation with illness severity. Comorbid diseases and clinical manifestations of severe COVID-19 patients vary substantially between latitudes and longitudes. Region-specific care should be considered to treat and improve the prognosis of COVID-19 patients.

Introduction: We compared the clinical characteristics of vaccinated and non-vaccinated Omicron patients in order to provide a reference for the clinical diagnosis and treatment of coronavirus disease 2019 (COVID-19). Methodology: This study included 360 patients diagnosed with COVID-19. The serum immunoglobulin G (IgG) and serum immunoglobulin M (IgM) antibody levels of the patients and the duration of virus shedding were analyzed according to age, gender, vaccine dose, and the time from the most recent vaccination to the onset of Omicron infection. Results: Age (OR = 0.974), days from last vaccination to onset ≤ 180 days (OR = 4.409), and booster dose of the vaccine (OR = 4.999) were protective factors associated with patients who were IgG antibody positive. The duration of virus shedding in IgG -antibody-positive patients was 9 (8-11) days; and this was significantly lower than that in IgG-antibody-negative patients, who had virus shedding duration of 10 (8-12) days (p < 0.05). Conclusions: Booster immunizations could increase IgG-antibody in patients who have already been infected with the Omicron variant and enhance immune protection. In addition, COVID-19 vaccination may shorten the duration of virus shedding.