Real-World COVID-19 Vaccine Protection Rates against Infection in the Delta and Omicron Eras.

The real-world vaccine protection rates (VPRs) against the severe acute respiratory syndrome coronavirus 2 (SARS­CoV­2) infection are critical in formulating future vaccination strategies against the virus. Based on a varying coefficient stochastic epidemic model, we obtain 7 countries' real-world VPRs using daily epidemiological and vaccination data, and find that the VPRs improved with more vaccine doses. The average VPR of the full vaccination was 82% (SE: 4%) and 61% (SE: 3%) in the pre-Delta and Delta-dominated periods, respectively. The Omicron variant reduced the average VPR of the full vaccination to 39% (SE: 2%). However, the booster dose restored the VPR to 63% (SE: 1%) which was significantly above the 50% threshold in the Omicron-dominated period. Scenario analyses show that the existing vaccination strategies have significantly delayed and reduced the timing and the magnitude of the infection peaks, respectively, and doubling the existing booster coverage would lead to 29% fewer confirmed cases and 17% fewer deaths in the 7 countries compared to the outcomes at the existing booster taking rates. These call for higher full vaccine and booster coverage for all countries.

Clinical and multimodal imaging features of acute macular neuroretinopathy lesions following recent SARS-CoV-2 infection.

AIM: To describe the clinical characteristics of eyes using multimodal imaging features with acute macular neuroretinopathy (AMN) lesions following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: Retrospective case series study. From December 18, 2022 to February 14, 2023, previously healthy cases within 1-week infection with SARS-CoV-2 and examined at Tianjin Eye Hospital to confirm the diagnosis of AMN were included in the study. Totally 5 males and 9 females [mean age: 29.93±10.32 (16-49)y] were presented for reduced vision, with or without blurred vision. All patients underwent best corrected visual acuity (BCVA), intraocular pressure, slit lamp microscopy, indirect fundoscopy. Simultaneously, multimodal imagings fundus photography (45° or 200° field of view) was performed in 7 cases (14 eyes). Near infrared (NIR) fundus photography was performed in 9 cases (18 eyes), optical coherence tomography (OCT) in 5 cases (10 eyes), optical coherence tomography angiography (OCTA) in 9 cases (18 eyes), and fundus fluorescence angiography (FFA) in 3 cases (6 eyes). Visual field was performed in 1 case (2 eyes). RESULTS: Multimodal imaging findings data from 14 patients with AMN were reviewed. All eyes demonstrated different extent hyperreflective lesions at the level of the inner nuclear layer and/or outer plexus layer on OCT or OCTA. Fundus photography (45° or 200° field of view) showed irregular hypo-reflective lesion around the fovea in 7 cases (14 eyes). OCTA demonstrated that the superficial retinal capillary plexus (SCP) vascular density, deep capillary plexus (DCP) vascular density and choriocapillaris (CC) vascular density was reduced in 9 case (18 eyes). Among the follow-up cases (2 cases), vascular density increased in 1 case with elevated BCVA; another case has vascular density decrease in one eye and basically unchanged in other eye. En face images of the ellipsoidal zone and interdigitation zone injury showed a low wedge-shaped reflection contour appearance. NIR image mainly show the absence of the outer retinal interdigitation zone in AMN. No abnormal fluorescence was observed in FFA. Corresponding partial defect of the visual field were visualized via perimeter in one case. CONCLUSION: The morbidity of SARS-CoV-2 infection with AMN is increased. Ophthalmologists should be aware of the possible, albeit rare, AMN after SARS-CoV-2 infection and focus on multimodal imaging features. OCT, OCTA, and infrared fundus phase are proved to be valuable tools for detection of AMN in patients with SARS-CoV-2.

Insights into COVID-19-associated critical illness: a narrative review.

Background and Objective: Since the outbreak of the 2019 novel coronavirus disease (COVID-19), acute respiratory distress syndrome (ARDS) and sepsis resulting from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have surged in intensive care units around the world. The heterogeneity of ARDS and sepsis has long been observed, and multiple subphenotypes and endotypes correlated with different outcomes and treatment response have been identified in the search for treatable traits. Despite their similarity to typical ARDS and sepsis, COVID-19-associated ARDS and sepsis harbor distinct features, raising the question as to whether they could be considered as subphenotypes or endotypes of the historical syndromes and, accordingly, benefit from specific therapeutic strategies. This review aimed to summarize and discuss the current knowledge of COVID-19-associated critical illness and the intrinsic subphenotypes or endotypes. Methods: Literature on the pathogenesis of COVID-19 and the subphenotyping of COVID-19-associated critical illness was derived from the PubMed database and reviewed. Key Content and Findings: Accumulating evidence, varying from clinical observation to basic research, has contributed to revealing the fundamental pathophysiological features of severe COVID-19 and has advanced our knowledge of the disease. COVID-19-associated ARDS and sepsis exhibit some distinctive features compared to the classic syndromes, including remarkable vascular abnormality and coagulopathy, and distinct respiratory mechanics and immune response. Some conventional subphenotypes derived from classic ARDS and sepsis have been validated in COVID-19, while novel subphenotypes and endotypes have also been identified in patients with this disease, who experience variable clinical outcomes and treatment responses. Conclusions: Subphenotyping of COVID-19-associated ARDS and sepsis can provide new insights into the development and management of these illnesses.

Testing and signal identification for two-sample high-dimensional covariances via multi-level thresholding

The paper considers testing and signal identification for covariance matrices from two populations of marginally sub-Gaussian distributed. A multi-level thresholding procedure is proposed for testing the equality of two high-dimensional covariance matrices, which is designed to detect sparse and faint differences between the covariances. A novel U-statistic composition is developed to establish the asymptotic distribution of the thresholding statistics in conjunction with the matrix blocking and the coupling techniques. It is shown that the proposed test is more powerful than the existing tests in detecting sparse and weak signals in covariances. Multiple testing procedures are constructed to discover different covariances and the sub-groups of variables with different covariance structures between the two populations. The proposed procedures are based on the multi-level thresholding test, which are able to control the false discovery proportion (FDP) with high power. Simulation experiments and a case study on the returns of the S&P 500 stocks before and after the COVID-19 pandemic are conducted to demonstrate and compare the utilities of the proposed methods.

AMPK directly phosphorylates TBK1 to integrate glucose sensing into innate immunity.

Nutrient sensing and damage sensing are two fundamental processes in living organisms. While hyperglycemia is frequently linked to diabetes-related vulnerability to microbial infection, how body glucose levels affect innate immune responses to microbial invasion is not fully understood. Here, we surprisingly found that viral infection led to a rapid and dramatic decrease in blood glucose levels in rodents, leading to robust AMPK activation. AMPK, once activated, directly phosphorylates TBK1 at S511, which triggers IRF3 recruitment and the assembly of MAVS or STING signalosomes. Consistently, ablation or inhibition of AMPK, knockin of TBK1-S511A, or increased glucose levels compromised nucleic acid sensing, while boosting AMPK-TBK1 cascade by AICAR or TBK1-S511E knockin improves antiviral immunity substantially in various animal models. Thus, we identify TBK1 as an AMPK substrate, reveal the molecular mechanism coupling a dual sensing of glucose and nuclei acids, and report its physiological necessity in antiviral defense.

[Clinical observation on filiform-fire needling of "Biaoben acupoint combination" for 33 cases of sequelae of coronavirus disease 2019 during recovery period].

OBJECTIVE: To observe the clinical therapeutic effect of filiform-fire needling of "Biaoben acupoint combination" on the sequelae of patients with coronavirus disease 2019 (COVID-19) during the recovery period. METHODS: A total of 33 patients with COVID-19 during the recovery period were treated with filiform-fire needling at the acupoints of Mingmen (GV 4), Shenzhu (GV 12), Gaohuang (BL 43), Zusanli (ST 36) and Shangjuxu (ST 37), etc., once every other day, 3 times a week, and 3 times was one course of treatment and totally 2 courses of treatment were required. The TCM symptom, Hamilton anxiety scale (HAMA) and Hamilton depression scale (HAMD) scores, pulmonary function indexes (forced vital capacity [FVC], forced expiratory volume in one second [FEV1], peak expiratory flow [PEF]) and chest CT imaging change were observed before and after treatment, and the therapeutic effect was evaluated. RESULTS: After treatment, the scores of TCM symptom, HAMA and HAMD were decreased compared with those before treatment (P<0.05), and the levels of FVC, FEV1 and PEF were increased compared with those before treatment (P<0.05), and the recovery rate of 22 patients with pulmonary ventilation dysfunction was 86.4% (19/22). After treatment, the lung shadow area was smaller than that before treatment (P<0.05). The effective rate of 25 patients with lung CT abnormalities was 84.0% (21/25). After treatment, 23 cases were cured, 5 cases were markedly effective, 4 cases were effective, 1 case was ineffective, the cured and markedly effective rate was 84.8%. CONCLUSION: The filiform-fire needling of "Biaoben acupoint combination" could significantly reduce the sequelae of cough, fatigue, chest tightness, etc. and mental symptoms such as anxiety and depression in patients with COVID-19 during the recovery period, and promote inflammatory exudation absorption of pulmonary lesion and improve lung ventilation function.

Identification of serum metabolites enhancing inflammatory responses in COVID-19.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is characterized by a strong production of inflammatory cytokines such as TNF and IL-6, which underlie the severity of the disease. However, the molecular mechanisms responsible for such a strong immune response remains unclear. Here, utilizing targeted tandem mass spectrometry to analyze serum metabolome and lipidome in COVID-19 patients at different temporal stages, we identified that 611 metabolites (of 1,039) were significantly altered in COVID-19 patients. Among them, two metabolites, agmatine and putrescine, were prominently elevated in the serum of patients; and 2-quinolinecarboxylate was changed in a biphasic manner, elevated during early COVID-19 infection but levelled off. When tested in mouse embryonic fibroblasts (MEFs) and macrophages, these 3 metabolites were found to activate the NF-κB pathway that plays a pivotal role in governing cytokine production. Importantly, these metabolites were each able to cause strong increase of TNF and IL-6 levels when administered to wildtype mice, but not in the mice lacking NF-κB. Intriguingly, these metabolites have little effects on the activation of interferon regulatory factors (IRFs) for the production of type I interferons (IFNs) for antiviral defenses. These data suggest that circulating metabolites resulting from COVID-19 infection may act as effectors to elicit the peculiar systemic inflammatory responses, exhibiting severely strong proinflammatory cytokine production with limited induction of the interferons. Our study may provide a rationale for development of drugs to alleviate inflammation in COVID-19 patients.

Relationship Between Plasma Vitamin C and COVID-19 Susceptibility and Severity: A Two-Sample Mendelian Randomization Study.

Background: Considering the antioxidant function of Vitamin C, also called ascorbic acid, it is widely used against viral infections such as coronavirus disease (COVID-19) based on in vitro, observational, and ecological studies. Many confounding factors that can affect Vitamin C levels. Thus, the association described to date may not be causal. To determine the causal relationship between genetically predicted plasma Vitamin C and COVID-19 susceptibility and severity, we performed two-sample Mendelian randomization (MR) based on large samples. Methods: The summary-level data for Vitamin C was obtained from a GWAS meta-analysis, which included 52,018 individuals from four studies of European ancestry. Data for COVID-19 HGI results were obtained from the meta-analysis of 35 GWASs with more than 1,000,000 subjects of European ancestry, including 32,494 cases with COVID-19 susceptibility and 1,316,207 controls, 9,986 cases with COVID-19 hospitalization and 1,877,672 controls, and 5,101 cases with COVID-19 severe disease and 1,383,241 controls. Mendelian randomization (MR) analysis was conducted to examine the effect of selected single nucleotide polymorphisms and COVID-19 susceptibility, hospitalization, disease severity. Several sensitivity analyses were performed with inverse-variance weighted (random-effect model), inverse variance weighted (fixed-effect model), weighted median, and maximum likelihood methods for estimating the causal effects. Results: In this MR study, genetic predisposition to the levels of plasma Vitamin C was not associated with COVID-19 susceptibility (OR: 0.99, 95% CI: 0.84-1.17, P = 0.91), hospitalization (OR: 1.10, 95% CI: 0.71-1.71, P = 0.67) and severity (OR: 0.83, 95% CI: 0.43-1.59, P = 0.58). The association was consistent in complementary analyses. No potential heterogeneities and directional pleiotropies were observed for the analysis results. Conclusion: According to our study, no correlation was observed between plasma Vitamin C levels and COVID-19 susceptibility and severity. Further studies in different ethnics are necessary to explore the potential role and mechanisms of circulating serum Vitamin C levels on COVID-19.

Physical Exercise Ameliorates Anxiety, Depression and Sleep Quality in College Students: Experimental Evidence from Exercise Intensity and Frequency.

BACKGROUND: The main purpose of this study was to investigate the effects of exercise intensity and exercise frequency on anxiety, depression and sleep quality in college students. METHODS: All participants came from a university in northeastern China. All participants were tested for Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and were diagnosed with anxiety disorders. The research subjects were divided into six groups, namely the low-intensity and low-frequency group (group 1), low-intensity and moderate-frequency group (group 2), low-intensity and high-frequency group (group 3), high-intensity and low-frequency group (group 4), and high-intensity and moderate-frequency group (group 5) and high-intensity and high-frequency group (group 6). The duration of each physical exercise for each group was 1 h. Participants' exercise intensity was monitored using Polar H10 HR sensors and the Borg RPE scale. The experiment was carried out for a total of 6 weeks. The researchers conducted pre- and post-test scores on the subjects' anxiety, depression and sleep quality through questionnaires. RESULTS: Exercise intensity improved anxiety and decreased symptoms of depression better than exercise frequency; sleep quality was more closely related to exercise intensity. CONCLUSION: Exercise intensity and exercise frequency have different effects on anxiety, depression and sleep quality improvement, indicating that exercise intensity and exercise frequency have different effects on anxiety, depression and sleep quality of college students.

[Thumb-tack needles based on "Biaoben acupoint compatibility" for sequela of COVID-19 during recovery period].

OBJECTIVE: To observe the effect of thumb-tack needles based on "Biaoben acupoint compatibility" on sequela symptoms, mental state and pulmonary ventilation function in patients with coronavirus disease 2019 (COVID-19) during recovery period. METHODS: Fifty cases of COVID-19 during recovery period were randomly divided into an observation group and a control group, 25 cases in each group. The patients in the observation group were treated with thumb-tack needles at Guanyuan (CV 4), Zusanli (ST 36) and Taiyuan (LU 9). The patients in the control group were treated with sham thumb-tack needles at identical acupoints as the observation group. The treatment in the two groups was given once a day, 7-day treatment was taken as a course of treatment, and totally two courses of treatment were given. The TCM symptom score, Hamilton anxiety scale (HAMA) score, Hamilton depression scale (HAMD) score, pulmonary function (forced vital capacity [FVC], forced expiratory volume in the first second [FEV1], peak expiratory flow [PEF]), the severity of pulmonary ventilation dysfunction and pulmonary imaging changes in the two groups were compared before and after treatment. RESULTS: Compared before treatment, the total scores and each item scores of TCM symptom scale, HAMA scores and HAMD scores in the two groups were reduced after treatment (P<0.05). Except for the symptom scores of dry throat and dry stool, the total score and each item score of TCM symptom scale, HAMA score and HAMD score in the observation group were lower than those in the control group (P<0.05). Compared before treatment, FVC, FEV1 and PEF in the two groups were increased after treatment (P<0.05), and those in the observation group were higher than the control group (P<0.05). The severity of pulmonary ventilation dysfunction in the two groups was reduced after treatment (P<0.05), and the severity in the observation group was better than that in the control group (P<0.05). After treatment, the lung shadow area in the two groups was decreased (P<0.05), and that in the observation group was smaller than the control group (P<0.05). The improvement of imaging change in the observation group was better than that in the control group (P<0.05). CONCLUSION: The thumb-tack needles based on "Biaoben acupoint compatibility" could significantly reduce the sequela symptoms, anxiety and depression in patients with COVID-19 during recovery stage, and improve the pulmonary ventilation function.

Practice and experience of regional medical center entrance linkage and closed-loop management under the wartime situation of the COVID-19 in China

On 28 July 2021, the first indigenous case of novel coronavirus pneumonia (COVID-19) emerged in Yangzhou, marking the beginning of a public health crisis caused by the new coronavirus pneumonia. It is a significant challenge for hospitals to carry out prevention and control measures to ensure the safety of medical professionals and patients when facing the changes in an epidemic situation. Subei People’s Hospital, as one of the first group of “Grade III-class A” hospitals in Jiangsu Province and the Yangzhou Regional Medical Centre, responded quickly and scientifically to prevent and control the disease. A closed-loop management system was implemented at the hospital entrance (consisting of the outpatient clinic, emergency clinic, fever clinic, and buffer ward) and an epidemic prevention and control group was established with the assistance of multiple departments. This group optimized the pre-screening and triage system, standardized the fever clinic consultation process, and improved the construction of an information-based prevention and control network so that patients were detected, diagnosed, isolated, and treated early. The emergency management capability was improved to achieve zero missed consultations of patients attending for COVID-19 and to effectively maintain medical order during this critical period. This current report systematically summarizes the operational practices and the effectiveness achieved by implementation of the entrance closed-loop management in the hospital and analyzed the key operational issues for future reference by medical institutions and management departments.

Toward an atomistic model of SARS-CoV-2 (preprint)

The causative pathogen of Coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an enveloped virus assembled by a lipid envelope, a positive-sense single-stranded RNA, and four structural proteins: the spike (S), membrane (M), envelope (E), and nucleocapsid (N) proteins. Extensive experimental and computational studies have been carried out to reveal the architecture of the virus, but an intact and high-resolution structure of the virus is still desired. In this work, we construct atomistic models of the intact SARS-CoV-2 (without complete RNA) by fully employing the latest cryo-ET data, in combination with the available experimentally resolved protein structures, structure prediction and modeling methods, as well as coarse-grained molecular dynamics (MD) simulations. The atomistic model will not only provide a 3D structure for scientific demonstration and education, but also offer a framework for future exascale all-atom MD simulations to understand the dynamics of the intact virus and its mutations.

A multi-class gene classifier for SARS-CoV-2 variants based on convolutional neural network (preprint)

Surveillance of circulating variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is of great importance in controlling the coronavirus disease 2019 (COVID-19) pandemic. We propose an alignment-free in silico approach for classifying SARS-CoV-2 variants based on their genomic sequences. A deep learning model was constructed utilizing a stacked 1-D convolutional neural network and multilayer perceptron (MLP). The pre-processed genomic sequencing data of the four SARS-CoV-2 variants were first fed to three stacked convolution-pooling nets to extract local linkage patterns in the sequences. Then a 2-layer MLP was used to compute the correlations between the input and output. Finally, a logistic regression model transformed the output and returned the probability values. Learning curves and stratified 10-fold cross-validation showed that the proposed classifier enables robust variant classification. External validation of the classifier showed an accuracy of 0.9962, precision of 0.9963, recall of 0.9963 and F1 score of 0.9962, outperforming other machine learning methods, including logistic regression, K-nearest neighbor, support vector machine, and random forest. By comparing our model with an MLP model without the convolution-pooling network, we demonstrate the essential role of convolution in extracting viral variant features. Thus, our results indicate that the proposed convolution-based multi-class gene classifier is efficient for the variant classification of SARS-CoV-2.

General recommendation for assessment and management on the risk of glucocorticoid-induced osteonecrosis in patients with COVID-19.

BACKGROUND/OBJECTIVE: Coronavirus disease 2019 (COVID-19) is a disaster in human medical history and glucocorticoids remain the most promising therapy. Osteonecrosis is a disease caused by reduced intraosseous blood flow to bones in the joints, which will rapidly induce joint destruction. Approximately one-third patients with severe acute respiratory syndrome (SARS) who received high cumulative doses and long treatment durations of glucocorticoids occurred osteonecrosis. Considering the similarity of SARS and COVID-19 on their pathogen, clinical characteristics, and therapeutic strategies, it is particularly desirable to investigate whether osteonecrosis will become a common sequela among convalescent COVID-19 patients. METHODS: This multi-strategy study was designed by integrating different research methods, such as meta-analysis, systematic review, and cross-sectional investigations to address above study objectives. At first, two meta-analyses were performed on the osteonecrosis incidence among SARS patients and the clinical data of glucocorticoid exposure among COVID-19 patients. Then, a systematic review of low-dosage glucocorticoid associated osteonecrosis and a cross-sectional investigation of glucocorticoid exposure of COVID-19 patients in Wuhan city of China were also conducted. Moreover, the pathogenesis, diagnosis, prevention, and treatment options for osteonecrosis patients with COVID-19 infection were further presented and discussed. RESULTS: Our meta-analysis showed that 32% of SARS patients had developed osteonecrosis after receiving glucocorticoid treatment with high dose, and our system review supported that low level glucocorticoid exposure might also lead to the occurrence of osteonecrosis. Similarly, 40% of COVID-19 patients had undergone glucocorticoid treatment according to our meta-analysis. The cross-sectional investigation in Wuhan city of China found that the average of cumulative glucocorticoid exposure level was 504 â€‹mg calculated by the dosage of methylprednisolone. Notably, a confirmed osteonecrosis case was identified from 1406 patients with COVID-19 during our cross-sectional investigation, implying that preventive management of osteonecrosis should be better started with regular clinical follow-up observation. CONCLUSION: Growing evidence of the glucocorticoid therapy for COVID-19 patients prompts us to establish risk-classification-based early screening and to introduce early prevention protocol of its associated osteonecrosis that will be of clinical significance in favor of improved prognosis of this disease. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: To establish risk-classification-based early screening and to introduce early prevention protocol of glucocorticoid-induced osteonecrosis will be of clinical significance in favor of improved prognosis of COVID-19.

Quality control of bedside DR images in severe and critical patients with corona virus disease 2019

Objective: To improve image quality of bedside digital radiography(DR) in severe and critical patients with corona virus disease 2019(COVID-19).

Favipiravir Versus Arbidol for Clinical Recovery Rate in Moderate and Severe Adult COVID-19 Patients: A Prospective, Multicenter, Open-Label, Randomized Controlled Clinical Trial.

Background: In addition to supportive therapy, antiviral therapy is an effective treatment for coronavirus disease 2019 (COVID-19). Objective: To compare the efficacy and safety of favipiravir and umifenovir (Arbidol) to treat COVID-19 patients. Methods: We conducted a prospective, randomized, controlled, open-label multicenter trial involving adult patients with COVID-19. Enrolled patients with initial symptoms within 12 days were randomly assigned in a 1:1 ratio to receive conventional therapy plus Arbidol (200 mg*3/day) or favipiravir (1600 mg*2/first day followed by 600 mg*2/day) for 7 days. The primary outcome was the clinical recovery rate at day 7 of drug administration (relief for pyrexia and cough, respiratory frequency ≤24 times/min; oxygen saturation ≥98%). Latency to relief for pyrexia and cough and the rate of auxiliary oxygen therapy (AOT) or noninvasive mechanical ventilation (NMV)/mechanical ventilation (MV) were the secondary outcomes. Safety data were collected for 17 days. Results: A total of 240 enrolled COVID-19 patients underwent randomization; 120 patients were assigned to receive favipiravir (116 assessed), and 120 patients were assigned to receive Arbidol (120 assessed). The clinical recovery rate at day 7 of drug administration did not significantly differ between the favipiravir group (71/116) and Arbidol group (62/120) (p = 0.1396, difference in recovery rate: 0.0954; 95% CI: -0.0305∼0.2213). Favipiravir contributed to relief for both pyrexia (difference: 1.70 days, p < 0.0001) and cough (difference: 1.75 days, p < 0.0001). No difference was observed in the AOT or NMV/MV rate (both p > 0.05). The most frequently observed favipiravir-associated adverse event was increased serum uric acid (16/116, OR: 5.52, p = 0.0014). Conclusion: Among patients with COVID-19, favipiravir, compared to Arbidol, did not significantly improve the clinical recovery rate at day 7. Favipiravir significantly improved the latency to relieve pyrexia and cough. Adverse effects caused by favipiravir are mild and manageable.

Better strategies for containing COVID-19 pandemic: a study of 25 countries via a vSIADR model.

We study epidemiological characteristics of 25 early COVID-19 outbreak countries, which emphasizes on the reproduction of infection and effects of government control measures. The study is based on a vSIADR model which allows asymptomatic and pre-diagnosis infections to reflect COVID-19 clinical realities, and a linear mixed-effect model to analyse the association between each country's control measures and the effective reproduction number R t . It finds significant effects of higher stringency measures in lowering the reproduction, and a significant shortening effect on the time to the epidemic turning point by applying stronger early counter measures. Epidemic projections under scenarios of the counter measures (China and Korea, the USA and the UK) show substantial reduction in the epidemic size and death by taking earlier and forceful actions. The governments' response before and after the start of the second wave epidemics were alarmingly weak, which made the average duration of the second wave more than doubled that of the first wave. We identify countries which urgently need to restore to at least the maximum stringency measures implemented so far in the pandemic in order to avoid even higher infection size and death.

Effects of corona virus disease-19 control measures on air quality in North China.

Corona virus disease-19 (COVID-19) has substantially reduced human activities and the associated anthropogenic emissions. This study quantifies the effects of COVID-19 control measures on six major air pollutants over 68 cities in North China by a Difference in Relative-Difference method that allows estimation of the COVID-19 effects while taking account of the general annual air quality trends, temporal and meteorological variations, and the spring festival effects. Significant COVID-19 effects on all six major air pollutants are found, with NO2 having the largest decline (-39.6%), followed by PM2.5 (-30.9%), O3 (-16.3%), PM10 (-14.3%), CO (-13.9%), and the least in SO2 (-10.0%), which shows the achievability of air quality improvement by a large reduction in anthropogenic emissions. The heterogeneity of effects among the six pollutants and different regions can be partly explained by coal consumption and industrial output data.