Randomized, placebo-controlled, single-blind phase 1 studies of the safety, tolerability, and pharmacokinetics of BRII-196 and BRII-198, SARS-CoV-2 spike-targeting monoclonal antibodies with an extended half-life in healthy adults.

Background: BRII-196 and BRII-198 are two anti-SARS-CoV-2 monoclonal neutralizing antibodies as a cocktail therapy for treating COVID-19 with a modified Fc region that extends half-life. Methods: Safety, tolerability, pharmacokinetics, and immunogenicity of BRII-196 and BRII-198 were investigated in first-in-human, placebo-controlled, single ascending dose phase 1 studies in healthy adults. 44 participants received a single intravenous infusion of single BRII-196 or BRII-198 up to 3,000 mg, or BRII-196 and BRII-198 combination up to 1500/1500 mg, or placebo and were followed up for 180 days. Primary endpoints were incidence of adverse events (AEs) and changes from pre-dose baseline in clinical assessments. Secondary endpoints included pharmacokinetics profiles of BRII-196/BRII-198 and detection of anti-drug antibodies (ADAs). Plasma neutralization activities against SARS-CoV-2 Delta live virus in comparison to post-vaccination plasma were evaluated as exploratory endpoints. Results: All infusions were well-tolerated without systemic or local infusion reactions, dose-limiting AEs, serious AEs, or deaths. Most treatment-emergent AEs were isolated asymptomatic laboratory abnormalities of grade 1-2 in severity. BRII-196 and BRII-198 displayed pharmacokinetics characteristic of Fc-engineered human IgG1 with mean terminal half-lives of 44.6-48.6 days and 72.2-83.0 days, respectively, with no evidence of interaction or significant anti-drug antibody development. Neutralizing activities against the live virus of the SARS-CoV-2 Delta variant were maintained in plasma samples taken on day 180 post-infusion. Conclusion: BRII-196 and BRII-198 are safe, well-tolerated, and suitable therapeutic or prophylactic options for SARS-CoV-2 infection. Clinical Trial Registration: ClinicalTrials.gov under identifiers NCT04479631, NCT04479644, and NCT04691180.

Randomized, placebo-controlled, single-blind phase 1 studies of the safety, tolerability, and pharmacokinetics of BRII-196 and BRII-198, SARS-CoV-2 spike-targeting monoclonal antibodies with an extended half-life in healthy adults

Background: BRII-196 and BRII-198 are two anti-SARS-CoV-2 monoclonal neutralizing antibodies as a cocktail therapy for treating COVID-19 with a modified Fc region that extends half-life. Methods: Safety, tolerability, pharmacokinetics, and immunogenicity of BRII-196 and BRII-198 were investigated in first-in-human, placebo-controlled, single ascending dose phase 1 studies in healthy adults. 44 participants received a single intravenous infusion of single BRII-196 or BRII-198 up to 3,000 mg, or BRII-196 and BRII-198 combination up to 1500/1500 mg, or placebo and were followed up for 180 days. Primary endpoints were incidence of adverse events (AEs) and changes from pre-dose baseline in clinical assessments. Secondary endpoints included pharmacokinetics profiles of BRII-196/BRII-198 and detection of anti-drug antibodies (ADAs). Plasma neutralization activities against SARS-CoV-2 Delta live virus in comparison to post-vaccination plasma were evaluated as exploratory endpoints. Results: All infusions were well-tolerated without systemic or local infusion reactions, dose-limiting AEs, serious AEs, or deaths. Most treatment-emergent AEs were isolated asymptomatic laboratory abnormalities of grade 1-2 in severity. BRII-196 and BRII-198 displayed pharmacokinetics characteristic of Fc-engineered human IgG1 with mean terminal half-lives of 44.6–48.6 days and 72.2–83.0 days, respectively, with no evidence of interaction or significant anti-drug antibody development. Neutralizing activities against the live virus of the SARS-CoV-2 Delta variant were maintained in plasma samples taken on day 180 post-infusion. Conclusion: BRII-196 and BRII-198 are safe, well-tolerated, and suitable therapeutic or prophylactic options for SARS-CoV-2 infection. Clinical Trial Registration:ClinicalTrials.gov under identifiers NCT04479631, NCT04479644, and NCT04691180.

Directional mutation and crossover boosted ant colony optimization with application to COVID-19 X-ray image segmentation.

This paper focuses on the study of Coronavirus Disease 2019 (COVID-19) X-ray image segmentation technology. We present a new multilevel image segmentation method based on the swarm intelligence algorithm (SIA) to enhance the image segmentation of COVID-19 X-rays. This paper first introduces an improved ant colony optimization algorithm, and later details the directional crossover (DX) and directional mutation (DM) strategy, XMACO. The DX strategy improves the quality of the population search, which enhances the convergence speed of the algorithm. The DM strategy increases the diversity of the population to jump out of the local optima (LO). Furthermore, we design the image segmentation model (MIS-XMACO) by incorporating two-dimensional (2D) histograms, 2D Kapur's entropy, and a nonlocal mean strategy, and we apply this model to COVID-19 X-ray image segmentation. Benchmark function experiments based on the IEEE CEC2014 and IEEE CEC2017 function sets demonstrate that XMACO has a faster convergence speed and higher convergence accuracy than competing models, and it can avoid falling into LO. Other SIAs and image segmentation models were used to ensure the validity of the experiments. The proposed MIS-XMACO model shows more stable and superior segmentation results than other models at different threshold levels by analyzing the experimental results.

BA.2.12.1, BA.4 and BA.5 escape antibodies elicited by Omicron infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron sublineages BA.2.12.1, BA.4 and BA.5 exhibit higher transmissibility than the BA.2 lineage1. The receptor binding and immune-evasion capability of these recently emerged variants require immediate investigation. Here, coupled with structural comparisons of the spike proteins, we show that BA.2.12.1, BA.4 and BA.5 (BA.4 and BA.5 are hereafter referred collectively to as BA.4/BA.5) exhibit similar binding affinities to BA.2 for the angiotensin-converting enzyme 2 (ACE2) receptor. Of note, BA.2.12.1 and BA.4/BA.5 display increased evasion of neutralizing antibodies compared with BA.2 against plasma from triple-vaccinated individuals or from individuals who developed a BA.1 infection after vaccination. To delineate the underlying antibody-evasion mechanism, we determined the escape mutation profiles2, epitope distribution3 and Omicron-neutralization efficiency of 1,640 neutralizing antibodies directed against the receptor-binding domain of the viral spike protein, including 614 antibodies isolated from people who had recovered from BA.1 infection. BA.1 infection after vaccination predominantly recalls humoral immune memory directed against ancestral (hereafter referred to as wild-type (WT)) SARS-CoV-2 spike protein. The resulting elicited antibodies could neutralize both WT SARS-CoV-2 and BA.1 and are enriched on epitopes on spike that do not bind ACE2. However, most of these cross-reactive neutralizing antibodies are evaded by spike mutants L452Q, L452R and F486V. BA.1 infection can also induce new clones of BA.1-specific antibodies that potently neutralize BA.1. Nevertheless, these neutralizing antibodies are largely evaded by BA.2 and BA.4/BA.5 owing to D405N and F486V mutations, and react weakly to pre-Omicron variants, exhibiting narrow neutralization breadths. The therapeutic neutralizing antibodies bebtelovimab4 and cilgavimab5 can effectively neutralize BA.2.12.1 and BA.4/BA.5, whereas the S371F, D405N and R408S mutations undermine most broadly sarbecovirus-neutralizing antibodies. Together, our results indicate that Omicron may evolve mutations to evade the humoral immunity elicited by BA.1 infection, suggesting that BA.1-derived vaccine boosters may not achieve broad-spectrum protection against new Omicron variants.

Multilevel threshold image segmentation for COVID-19 chest radiography: A framework using horizontal and vertical multiverse optimization.

COVID-19 is currently raging worldwide, with more patients being diagnosed every day. It usually is diagnosed by examining pathological photographs of the patient's lungs. There is a lot of detailed and essential information on chest radiographs, but manual processing is not as efficient or accurate. As a result, how efficiently analyzing and processing chest radiography of COVID-19 patients is an important research direction to promote COVID-19 diagnosis. To improve the processing efficiency of COVID-19 chest films, a multilevel thresholding image segmentation (MTIS) method based on an enhanced multiverse optimizer (CCMVO) is proposed. CCMVO is improved from the original Multi-Verse Optimizer by introducing horizontal and vertical search mechanisms. It has a more assertive global search ability and can jump out of the local optimum in optimization. The CCMVO-based MTIS method can obtain higher quality segmentation results than HHO, SCA, and other forms and is less prone to stagnation during the segmentation process. To verify the performance of the proposed CCMVO algorithm, CCMVO is first compared with DE, MVO, and other algorithms by 30 benchmark functions; then, the proposed CCMVO is applied to image segmentation of COVID-19 chest radiography; finally, this paper verifies that the combination of MTIS and CCMVO is very successful with good segmentation results by using the Feature Similarity Index (FSIM), the Peak Signal to Noise Ratio (PSNR), and the Structural Similarity Index (SSIM). Therefore, this research can provide an effective segmentation method for a medical organization to process COVID-19 chest radiography and then help doctors diagnose coronavirus pneumonia (COVID-19).

One-year follow-up of 18 women who infected COVID-19 while pregnant.

Data about the sequelae of women who infected COVID-19 while pregnant are scarce. We aimed to describe the prevalence of symptoms, pulmonary functions, and radiological changes at a follow-up of 12 months in 18 pregnant women who developed COVID-19 at different gestational ages. Our results showed that most women who infected COVID-19 while pregnant experienced a progressive improvement of their symptoms within 12 months, however, some still had little COVID-related symptoms but without a reduced quality of life. All their 18 newborns were growing up healthy.

PCSK9 inhibitor recaticimab for hypercholesterolemia on stable statin dose: a randomized, double-blind, placebo-controlled phase 1b/2 study.

BACKGROUND: Recaticimab (SHR-1209, a humanized monoclonal antibody against PCSK9) showed robust LDL-C reduction in healthy volunteers. This study aimed to further assess the efficacy and safety of recaticimab in patients with hypercholesterolemia. METHODS: In this randomized, double-blind, placebo-controlled phase 1b/2 trial, patients receiving stable dose of atorvastatin with an LDL-C level of 2.6 mmol/L or higher were randomized in a ratio of 5:1 to subcutaneous injections of recaticimab or placebo at different doses and schedules. Patients were recruited in the order of 75 mg every 4 weeks (75Q4W), 150Q8W, 300Q12W, 150Q4W, 300Q8W, and 450Q12W. The primary endpoint was percentage change in LDL-C from the baseline to end of treatment (i.e., at week 16 for Q4W and Q8W schedule and at week 24 for Q12W schedule). RESULTS: A total of 91 patients were enrolled and received recaticimab and 19 received placebo. The dose of background atorvastatin in all 110 patients was 10 or 20 mg/day. The main baseline LDL-C ranged from 3.360 to 3.759 mmol/L. The least-squares mean percentage reductions in LDL-C from baseline to end of treatment relative to placebo for recaticimab groups at different doses and schedules ranged from -48.37 to -59.51%. No serious treatment-emergent adverse events (TEAEs) occurred. The most common TEAEs included upper respiratory tract infection, increased alanine aminotransferase, increased blood glucose, and increased gamma-glutamyltransferase. CONCLUSION: Recaticimab as add-on to moderate-intensity statin therapy significantly and substantially reduced the LDL-C level with an infrequent administration schedule (even given once every 12 weeks), compared with placebo. TRIAL REGISTRATION: ClinicalTrials.gov , number NCT03944109.

Horizontal and vertical search artificial bee colony for image segmentation of COVID-19 X-ray images.

The artificial bee colony algorithm (ABC) has been successfully applied to various optimization problems, but the algorithm still suffers from slow convergence and poor quality of optimal solutions in the optimization process. Therefore, in this paper, an improved ABC (CCABC) based on a horizontal search mechanism and a vertical search mechanism is proposed to improve the algorithm's performance. In addition, this paper also presents a multilevel thresholding image segmentation (MTIS) method based on CCABC to enhance the effectiveness of the multilevel thresholding image segmentation method. To verify the performance of the proposed CCABC algorithm and the performance of the improved image segmentation method. First, this paper demonstrates the performance of the CCABC algorithm itself by comparing CCABC with 15 algorithms of the same type using 30 benchmark functions. Then, this paper uses the improved multi-threshold segmentation method for the segmentation of COVID-19 X-ray images and compares it with other similar plans in detail. Finally, this paper confirms that the incorporation of CCABC in MTIS is very effective by analyzing appropriate evaluation criteria and affirms that the new MTIS method has a strong segmentation performance.

Treatment of Coronavirus Disease 2019 Patients With Prolonged Postsymptomatic Viral Shedding With Leflunomide: A Single-center Randomized Controlled Clinical Trial.

BACKGROUND: We aimed to evaluate the efficacy and safety of leflunomide, an approved dihydroorotate dehydrogenase inhibitor, to treat coronavirus disease 2019 (COVID-19) patients with prolonged postsymptomatic viral shedding. METHODS: We conducted a prospective, randomized controlled, open-label trial involving hospitalized adult COVID-19 patients with prolonged polymerase chain reaction (PCR) positivity. Patients were randomly assigned to receive either leflunomide (50 mg every 12 hours, 3 consecutive times, orally; then 20 mg once daily for 8 days), in addition to nebulized interferon alpha 2a (IFN-α-2a, 3 million IU each time, twice daily for 10 days), or nebulized IFN-α-2a alone for 10 days. The primary endpoint was the duration of viral shedding. RESULTS: A total of 50 COVID-19 patients with prolonged PCR positivity were randomized into 2 groups: 26 were assigned to the leflunomide plus IFN-α-2a group, and 24 were assigned to the interferon-alone group. Treatment with leflunomide was not associated with a difference from the interferon-alone group in the duration of viral shedding (hazard ratio for negative reverse-transcription PCR, 0.70 [95% confidence interval, .391-1.256]; P = .186). In addition, the patients given leflunomide did not have a substantially shorter length of hospital stay than patients treated with interferon alone, with median durations of 29.0 (interquartile range [IQR], 19.3-47.3) days and 33.0 (IQR, 29.3-42.8) days, respectively (P = .170). Two leflunomide recipients were unable to complete the full 10-day course of administration due to adverse events. CONCLUSIONS: In COVID-19 patients with prolonged PCR positivity, no benefit in terms of the duration of viral shedding was observed with the combined treatment of leflunomide and IFN-α-2a beyond IFN-α-2a alone.

Clinical Efficacy of Corticosteroids in the Early Stages of Deterioration in COVID-19 Pneumonia.

BACKGROUND: The World Health Organization (WHO) strongly suggests using corticosteroids in patients with severe coronavirus disease 2019 (COVID-19). Similarly, a large randomized controlled clinical trial (RCT) in the UK found that dexamethasone effectively reduced the mortality rate in severe COVID-19 patients. However, the safety profile of corticosteroids has been a controversial area of study. CASE DESCRIPTION: A case of a COVID-19 patient is described and the clinical characteristics are observed as the mildly symptomatic patient progresses into a critically ill patient and during their dramatic improvement with corticosteroid therapy in the early stage of the deterioration process with COVID-19 pneumonia. CONCLUSION: The most suitable timing and dosage for the use of corticosteroids to maximize its effect during the worsening of COVID-19 pneumonia are discussed. One of the main pathophysiological hypotheses for severe COVID-19 patients is related to cytokine storm and virus load, which can be effectively treated with corticosteroid therapy.

Ant colony optimization with Cauchy and greedy Levy mutations for multilevel COVID 19 X-ray image segmentation.

This paper focuses on the study of multilevel COVID-19 X-ray image segmentation based on swarm intelligence optimization to improve the diagnostic level of COVID-19. We present a new ant colony optimization with the Cauchy mutation and the greedy Levy mutation, termed CLACO, for continuous domains. Specifically, the Cauchy mutation is applied to the end phase of ant foraging in CLACO to enhance its searchability and to boost its convergence rate. The greedy Levy mutation is applied to the optimal ant individuals to confer an improved ability to jump out of the local optimum. Furthermore, this paper develops a novel CLACO-based multilevel image segmentation method, termed CLACO-MIS. Using 2D Kapur's entropy as the CLACO fitness function based on 2D histograms consisting of non-local mean filtered images and grayscale images, CLACO-MIS was successfully applied to the segmentation of COVID-19 X-ray images. A comparison of CLACO with some relevant variants and other excellent peers on 30 benchmark functions from IEEE CEC2014 demonstrates the superior performance of CLACO in terms of search capability, and convergence speed as well as ability to jump out of the local optimum. Moreover, CLACO-MIS was shown to have a better segmentation effect and a stronger adaptability at different threshold levels than other methods in performing segmentation experiments of COVID-19 X-ray images. Therefore, CLACO-MIS has great potential to be used for improving the diagnostic level of COVID-19. This research will host a webservice for any question at https://aliasgharheidari.com.

Sustainable Allocation Model of Construction Workforce for Work Resumption during COVID-19

COVID-19 has posed challenges for the construction industry, such as precise pandemic control, sustainable labor relations, and loss minimization. In response to these challenges, this study has developed a decision model that optimizes workforce allocation for projects to achieve sustainable workforce management, a tradeoff between pandemic prevention and work resumption. The priority of project resumption was evaluated using basic characteristics, the long- and short-term strategies, and the regional pandemic situation. The energy level of skilled workers was graded according to construction team size, skill level, and experience. Sustainable allocation principles and paths were explored to target four different types of work resumption plans. We used the cellular automaton (CA) technique to simulate the sustainable allocation model. We also analyzed the similarity function of energy levels and the time-cost function of allocation. The case study of the SGJ Construction demonstrates that this allocation model can accurately simulate work resumption and provide a sustainable allocation decisions and tools under pandemic. Also, it implies balanced interests and concerns between construction companies and the society for work resumption during COVID-19.

The Nature of Crisis: Can Covid-19 Reveal the Deficiencies in Global Economy Governance?

The presented paper is devoted to the impact of the crisis as a philosophical and economic paradox on the modern civilization. How inevitable are crises? Are there universal methods for avoiding crisis situations? How effective are the anti-crisis paradigms implemented at the previous crisis stages of human development? These issues are considered by the authors in the framework of the study.

Repurposed Tocilizumab in Patients with Severe COVID-19.

The coronavirus disease 2019 (COVID-19) has caused a global pandemic, resulting in considerable morbidity and mortality. Tocilizumab, an inhibitor of IL-6, has been widely repurposed as a treatment of severely ill patients without robust evidence supporting its use. In this study, we aimed to systematically describe the effectiveness of treatment and prevention of the cytokine storms in COVID-19 patients with tocilizumab. In this multicentered retrospective and observational cohort study, 65 patients with COVID-19 receiving tocilizumab and 130 not receiving tocilizumab were propensity score matched at a ratio of 2:1 based on age, sex, and comorbidities from January 20, 2020 to March 18, 2020 in Wuhan, China. After adjusting for confounding, the detected risk for in-hospital death was lower in the tocilizumab group versus nontocilizumab group (hazard ratio = 0.47; 95% confidence interval = 0.25-0.90; p = 0.023). Moreover, use of tocilizumab was associated with a lower risk of acute respiratory distress syndrome (odds ratio = 0.23; 95% confidence interval = 0.11-0.45; p < 0.0001). Furthermore, patients had heightened inflammation and more dysregulated immune cells before treatment, which might aggravate disease progression. After tocilizumab administration, abnormally elevated IL-6, C-reactive protein, fibrinogen, and activated partial thromboplastin time decreased. Tocilizumab may be of value in prolonging survival in patients with severe COVID-19, which provided a novel strategy for COVID-19-induced cytokine release syndrome. Our findings could inform bedside decisions until data from randomized, controlled clinical trials become available.

Clinical Courses and Outcomes of Patients with Chronic Obstructive Pulmonary Disease During the COVID-19 Epidemic in Hubei, China.

Purpose: In this study, we investigated the acute exacerbation and outcomes of COPD patients during the outbreak of COVID-19 and evaluated the prevalence and mortality of COPD patients with confirmed COVID-19. Methods: A prospectively recruited cohort of 489 COPD patients was retrospectively followed-up for their conditions during the COVID-19 pandemic from December 2019 to March 2020 in Hubei, China. In addition, the features of 821 discharged patients with confirmed COVID-19 were retrospectively analyzed. Results: Of the 489 followed-up enrolled COPD patients, 2 cases were diagnosed as confirmed COVID-19, and 97 cases had exacerbations, 32 cases of which were hospitalized, and 14 cases died. Compared with the 6-month follow-up results collected 1 year ago, in 307 cases of this cohort, the rates of exacerbations and hospitalization of the 489 COPD patients during the last 4 months decreased, while the mortality rate increased significantly (2.86% vs 0.65%, p=0.023). Of the 821 patients with COVID-19, 37 cases (4.5%) had pre-existing COPD. Of 180 confirmed deaths, 19 cases (10.6%) were combined with COPD. Compared to COVID-19 deaths without COPD, COVID-19 deaths with COPD had higher rates of coronary artery disease and/or cerebrovascular diseases. Old age, low BMI and low parameters of lung function were risk factors of all-cause mortality for COVID-19 patients with pre-existing COPD. Conclusion: Our findings imply that acute exacerbations and hospitalizations of COPD patients were infrequent during the COVID-19 pandemic. However, COVID-19 patients with pre-existing COPD had a higher risk of all-cause mortality.

Chemoprophylaxis, diagnosis, treatments, and discharge management of COVID-19: An evidence-based clinical practice guideline (updated version).

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a rapidly spreading illness, coronavirus disease 2019 (COVID-19), affecting more than seventeen million people around the world. Diagnosis and treatment guidelines for clinicians caring for patients are needed. In the early stage, we have issued "A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumonia (standard version)"; now there are many direct evidences emerged and may change some of previous recommendations and it is ripe for develop an evidence-based guideline. We formed a working group of clinical experts and methodologists. The steering group members proposed 29 questions that are relevant to the management of COVID-19 covering the following areas: chemoprophylaxis, diagnosis, treatments, and discharge management. We searched the literature for direct evidence on the management of COVID-19, and assessed its certainty generated recommendations using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Recommendations were either strong or weak, or in the form of ungraded consensus-based statement. Finally, we issued 34 statements. Among them, 6 were strong recommendations for, 14 were weak recommendations for, 3 were weak recommendations against and 11 were ungraded consensus-based statement. They covered topics of chemoprophylaxis (including agents and Traditional Chinese Medicine (TCM) agents), diagnosis (including clinical manifestations, reverse transcription-polymerase chain reaction (RT-PCR), respiratory tract specimens, IgM and IgG antibody tests, chest computed tomography, chest x-ray, and CT features of asymptomatic infections), treatments (including lopinavir-ritonavir, umifenovir, favipiravir, interferon, remdesivir, combination of antiviral drugs, hydroxychloroquine/chloroquine, interleukin-6 inhibitors, interleukin-1 inhibitors, glucocorticoid, qingfei paidu decoction, lianhua qingwen granules/capsules, convalescent plasma, lung transplantation, invasive or noninvasive ventilation, and extracorporeal membrane oxygenation (ECMO)), and discharge management (including discharge criteria and management plan in patients whose RT-PCR retesting shows SARS-CoV-2 positive after discharge). We also created two figures of these recommendations for the implementation purpose. We hope these recommendations can help support healthcare workers caring for COVID-19 patients.

Indirect implications of COVID-19 prevention strategies on non-communicable diseases : An Opinion Paper of the European Society of Hypertension Working Group on Hypertension and Cardiovascular Risk Assessment in Subjects Living in or Emigrating from Low Resource Settings.

BACKGROUND: After its outbreak in China, the novel COronaVIrus Disease 19 is spreading across the globe. It is an emergency the world has never seen before. MAIN TEXT: The attention of health systems is mainly focused on COronaVIrus Disease 19 patients and on the risk that intensive care units might be overwhelmed by the serious pulmonary complications. Different countries are also attempting to establish infection prevention and control strategies which proved effective in China where the outbreak was initially reported. We reflect on important lessons to be learnt from different countries. The effects that infection prevention and control strategies, such as social distancing or isolation, can have on the care of millions of patients with non-communicable diseases, who may be indirectly affected, have not been taken into consideration so much. CONCLUSIONS: When dealing with COronaVIrus Disease 19, policy makers and healthcare personnel should consider the indirect effects on the treatment of non-communicable diseases.

Asymptomatic infection by SARS-CoV-2 in healthcare workers: A study in a large teaching hospital in Wuhan, China.

OBJECTIVES: To investigate the proportion and characteristics of asymptomatic infection among healthcare workers (HCWs). METHODS: This study retrospectively investigated 1407 HCWs who were screened for COVID-19 by chest computed tomography (CT) scans and nasopharyngeal swabs for SARS-CoV-2 nucleic acid. Demographics, CT features, nasopharyngeal swabs, baseline symptoms, and laboratory data were collected. RESULTS: Of 1407 HCWs, 235 had symptoms and 1172 were asymptomatic close contacts, of which, 107 were symptomatic cases and 84 were close contacts who had abnormal CT findings. Of 152 symptomatic individuals and 908 close contacts tested for SARS-CoV-2 nucleic acid, 122 symptomatic cases and 38 close contacts had positive reverse-transcriptase real-time polymerase chain (RT-PCR) test results. The rate of confirmed asymptomatic infections was 4.2% (38/908). Both symptomatic and asymptomatic infected cases had high titrations of specific IgG or had ≥four-fold increase in IgG during convalescence compared with the acute phase. Combining the RT-PCR tests and serological findings, the rate of asymptomatic infections was 9.7% (88/908). In terms of the duration of viral shedding, there was no significant difference between symptomatic mild/moderate participants and asymptomatic infections. CONCLUSIONS: The findings demonstrated that a high rate of asymptomatic SARS-CoV-2 carriers existed among healthcare worker close contacts during the outbreak of COVID-19.