[Research on the interaction between COVID-19 and influenza].

Since the global pandemic of COVID-19, different countries have implemented various prevention and control measures, which has affected the epidemic characteristics of respiratory infectious diseases such as influenza. From 2020 to 2021, the level of influenza activity was relatively low, but it is necessary to be alert that with the adjustment of national prevention and control measures, influenza may have a relatively strong epidemic rebound. In order to deal with influenza epidemic, experts were organized to publish a series of influenza studies in this issue, suggesting that influenza prevention and control cannot be underestimated during the COVID-19 pandemic. It is suggested to carry out research on the interaction between COVID-19 and influenza to explore the epidemic characteristics of the disease, develop new technologies and tools to improve the efficiency of monitoring and early warning, identify obstacles to vaccination, promote the scientific implementation of intervention measures, and achieve joint prevention and control of multiple diseases.

[Strengthen evaluation of vaccine effectiveness to facilitate scientific and targeted prevention and control of the COVID-19 pandemic].

The COVID-19 continues to spread throughout the world, and local clusters and outbreaks related to overseas imports have occurred in many places in China. Vaccination against COVID-19 is one of the most effective tools to prevent disease, severe illness and death. For vaccines developed and used by China, it is particularly important for scientific and targeted prevention and control to study different outbreak scenarios, to conduct in-depth real-world research on SARS-CoV-2 variants, and to further promote vaccine development and technical reserves. This article commented the effectiveness of COVID-19 vaccine, and prospected the future research on vaccine efficacy, immunization strategy and vaccine development, which provided evidence for optimizing vaccination strategy.

An interpretable deep learning workflow for discovering subvisual abnormalities in CT scans of COVID-19 inpatients and survivors

Tremendous efforts have been made to improve diagnosis and treatment of COVID-19, but knowledge on long-term complications is limited. In particular, a large portion of survivors has respiratory complications, but currently, experienced radiologists and state-of-the-art artificial intelligence systems are not able to detect many abnormalities from follow-up computerized tomography (CT) scans of COVID-19 survivors. Here we propose Deep-LungParenchyma-Enhancing (DLPE), a computer-aided detection (CAD) method for detecting and quantifying pulmonary parenchyma lesions on chest CT. Through proposing a number of deep-learning-based segmentation models and assembling them in an interpretable manner, DLPE removes irrelevant tissues from the perspective of pulmonary parenchyma, and calculates the scan-level optimal window, which considerably enhances parenchyma lesions relative to the lung window. Aided by DLPE, radiologists discovered novel and interpretable lesions from COVID-19 inpatients and survivors, which were previously invisible under the lung window. Based on DLPE, we removed the scan-level bias of CT scans, and then extracted precise radiomics from such novel lesions. We further demonstrated that these radiomics have strong predictive power for key COVID-19 clinical metrics on an inpatient cohort of 1,193 CT scans and for sequelae on a survivor cohort of 219 CT scans. Our work sheds light on the development of interpretable medical artificial intelligence and showcases how artificial intelligence can discover medical findings that are beyond sight. Respiratory complications after a COVID infection are a growing concern, but follow-up chest CT scans of COVID-19 survivors hardly present any recognizable lesions. A deep learning-based method was developed that calculates a scan-specific optimal window and removes irrelevant tissues such as airways and blood vessels from images with segmentation models, so that subvisual abnormalities in lung scans become visible.

[Promoting influenza vaccination during 2021-2022 season from the perspective of population medicine].

The lower temperature in autumn-winter provides favorable conditions for the survival and spread of respiratory infectious diseases such as the corona virus disease 2019 (COVID-19) and influenza. It is likely that there will be a co-circulation of respiratory pathogens such as SARS-CoV-2 and influenza. In order to promote the prevention and control of influenza and the application of influenza vaccination during the COVID-19 pandemic in China, we separately discussed the risk of influenza epidemic in the 2021-2022 season, the influenza vaccination policies, and advocate influenza vaccination during the COVID-19 pandemic from the perspective of population medicine. We appeal that COVID-19 vaccination cannot delay the normal delivery of other vaccines in the national immunization programs and non-Expanded Program on Immunization (EPI) vaccines. Promoting influenza vaccination policies and improving immunization service convenience are necessary for increasing influenza vaccine coverage, protecting public health and assisting COVID-19 response.

[Summary and prospect of early warning models and systems for infectious disease outbreaks].

This paper summarizes the basic principles and models of early warning for infectious disease outbreaks, introduces the early warning systems for infectious disease based on different data sources and their applications, and discusses the application potential of big data and their analysing techniques, which have been studied and used in the prevention and control of COVID-19 pandemic, including internet inquiry, social media, mobile positioning, in the early warning of infectious diseases in order to provide reference for the establishment of an intelligent early warning mechanism and platform for infectious diseases based on multi-source big data.

[Evaluation of demand of resources for laboratory testing and prevention and control of COVID-19 in the context of global pandemic].

Objective: To rapidly evaluate the level of healthcare resource demand for laboratory testing and prevention and control of corona virus disease 2019 (COVID-19) in different epidemic situation, and prepare for the capacity planning, stockpile distribution, and funding raising for infectious disease epidemic response. Methods: An susceptible, exposed, infectious, removed infectious disease dynamics model with confirmed asymptomatic infection cases and symptomatic hospitalized patients was introduced to simulate different COVID-19 epidemic situation and predict the numbers of hospitalized or isolated patients, and based on the current COVID-19 prevention and control measures in China, the demands of resources for laboratory testing and prevention and control of COVID-19 were evaluated. Results: When community or local transmission or outbreaks occur and total population nucleic acid testing is implemented, the need for human resources is 3.3-89.1 times higher than the reserved, and the current resources of medical personal protective equipment and instruments can meet the need. The surge in asymptomatic infections can also increase the human resource demand for laboratory testing and pose challenge to the prevention and control of the disease. When vaccine protection coverage reach ≥50%, appropriate adjustment of the prevention and control measures can reduce the need for laboratory and human resources. Conclusions: There is a great need in our country to reserve the human resources for laboratory testing and disease prevention and control for the response of the possible epidemic of COVID-19. Challenges to human resources resulted from total population nucleic acid testing and its necessity need to be considered. Conducting non-pharmaceutical interventions and encouraging more people to be vaccinated can mitigate the shock on healthcare resource demand in COVID-19 prevention and control.

[Promote multidisciplinary integration, and strengthen capacities on prevention, control and pandemic preparedness of influenza].

Series of the studies and consensus on the basic research on seasonal and animal influenza virus, clinical characteristics of patients with pneumonia caused by influenza A (H1N1) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), disease burden of influenza, and promotion of influenza vaccination for the elderly were published in this special issue, aiming to describe the feature of influenza virological and clinical characteristics, health and economic burden, and vaccination. These researches emphasized the importance of the integration between basic medicine, clinical medicine, public health and preventive medicine in the prevention and control of infectious diseases. Based on the concept of population medicine, promoting the integration of multidisciplinary and strengthening prevention, control and pandemic preparedness on influenza, corona virus disease 2019 and other infectious diseases, could consolidate the foundation of surveillance and early warning, prevention and control, diagnosis and treatment of emerging infectious diseases, as well as improve the ability of emergency preparedness for public health events.

[Experience and thinking on the normalization stage of prevention and control of COVID-19 in China].

COVID-19 is an important public health issue of great concern at home and abroad, and it is still in the state of global pandemic. During the normalization stage of prevention and control of the epidemic of COVID-19, China effectively controlled the outbreak and spread of the epidemic by adopting the strategy of "import of external prevention and rebound of internal prevention", and effectively reduced the occurrence of death cases. The social economy recovered quickly, and various measures were highly recognized by the public, and the positive trend of the epidemic continued to consolidate. At present, although the spread of the local epidemic has been basically stopped, the international epidemic continues to rise rapidly, and the pressure of "imported prevention and control" in China continues to increase. Considering the characteristics of the normalization of epidemic prevention and control and the particularity of the virus, the connotation of the normalization of epidemic prevention and control should be understood scientifically. The prevention and control goal of the epidemic in the normalization stage should be to maximize early detection, early treatment and early disposal, and resolutely prevent the continuous spread of the epidemic in communities, that is, to prevent the infection as much as possible, and resolutely prevent the rebound (sustained spread in communities), rather than "zero infection". The prevention and control policy of "timely detection, rapid disposal, precise management and control, and effective treatment" has been implemented in various localities, and a series of effective and regular experience in prevention and control has been formed in the practice of prevention and control. Winter and spring are the key periods for the prevention and control of the epidemic. We should continue to work together to prevent and control the epidemic, fulfill the responsibilities of all parties, and prevent and control the epidemic in a scientific and effective way.

[Epidemiological study design of asymptomatic infection of the 2019 novel coronavirus].

COVID-19 is caused by the 2019 novel coronavirus (2019-nCoV). COVID-19 clinical cases are considered as the principal source of infection, however, asymptomatic cases may also play a role in the transmission. Significant gap exists in terms of the proportion or prevalence and transmissibility of asymptomatic cases. This study design plans to use data from areas with different epidemiological profiles to investigate the COVID-19 epidemic in China. In each selected region, both general community residents and key populations at high risk of COVID-19 infection, including recovered COVID-19 cases, close contacts of confirmed COVID-19 cases, medical professionals, investigators at CDCs, and visitors to fever clinics, will be recruited and examined for viral RNA of 2019-nCoV and serum antibodies. Prevalence and characterization of asymptomatic cases will be determined, stratified by varied demographics and exposure risk. During the follow-up, the change in the serum antibodies will be studied prospectively in the symptomatic and asymptomatic cases to address the scientific and public health concerns of infectivity and transmissibility of 2019-nCoV.

[Thoughts on the outbreak phases of the COVID-19 changed from emergency response to the combination of emergent response and regular prevention and control activities].

Given the scope and speed of the spread, the COVID-19 pandemic is not only complex but dangerous. Complicated objective factors such as the long-term existence of source of infection, difficulty in completely blocking the transmission route and a large susceptible population suggested that the COVID-19 pandemic might stay with us for long term. Therefore, we should be ready for a tough and long-term battle against the COVID-19 epidemic. The strategy should adhere to the principle of combining emergency response with regular prevention and control measures, and all efforts should be well harnessed in a coordinated way to keep the epidemic under control.

[Scenario-based study of medical resource requirement rapid assessment under the COVID-19 pandemic].

Objective: COVID-19 outbreak is still under global pandemic. China is facing the risks of importation and local rebound of COVID-19. Under the circumstances, preparations for medical resources are in urgently needed. Methods: Based on current understanding of the disease, we set up five scenarios and use the infectious disease transmission dynamic and pandemic theoretical static models to evaluate the demand for medical resources. Results: Different epidemic strength and strategies of disease control and prevention resulted in different levels of medical resource request, and active control strategy and effective measures could significantly decrease the requirement. During the epidemic rising phase, the cost of prevention and control measures and the requirement of professional response capacities would increase with potential high risk of medical resource demand sharply increasing. Conclusion: Regions with different economic level, population scale, and different prevention and control capabilities should all initiate scientific assessment of medical resource requirement under emergency response and prepare for possible future rebound and epidemic.