Chapter 7 - Better understanding and control of new coronavirus infection

We have been continuously deepening our understanding of 2019 coronavirus disease (COVID-19)—an emerging disease. Further knowledge on varying clinical manifestations, phenotypes, clinical course, acute and chronic conditions, susceptibility, as well as research to improve our ability in identification of susceptible populations and tracking the direction of evolution of the virus, are urgently needed.

Chapter 6 - Prevention and disease control of COVID-19

The control of infectious disease is more dependent on prevention than on treatment. The first task is to isolate the source of infection. Suspected patients, mildly affected patients, and close contacts of confirmed cases should be placed under medical observation. No matter whether there is an etiological diagnosis or not, suspected patients should be kept in strict isolation. It is difficult to identify the source of infection completely unless compulsory measures are taken, such as door-to-door screening. Therefore, the focus of prevention is how to cut off the transmission routes. Given that droplet transmission and contact transmission appear to be the main routes of transmission of COVID-19, the general public need to refrain from going outdoors as much as possible, wear masks in public, and keep good hygiene including frequent handwashing, and wiping and disinfecting door handles and elevator buttons. It is recommended to stop using central air-conditioning because COVID-19 may also spread through aerosol transmission.

Chapter 5 - Treatment of COVID-19

Suspected and confirmed cases should be treated in a designated hospital with effective isolation and protective conditions. The isolation condition of suspected cases should be the highest, and treatment should be carried out in a single room instead of mixed accommodation. Only confirmed cases should be admitted to the same ward, and critically ill patients should be admitted to ICU as soon as possible. At this stage, asymptomatic infected persons should also be isolated for observation. If a severe epidemic occurs in the area and medical resources are limited, mild cases and asymptomatic infected persons can be treated and observed at home, but registration and management should be carried out by the local disease prevention and control institutions and community health service centers, so as to guide, observe, and treat the quarantine at home. Moreover, the referral and transfer of severe patients should be safe, evaluated well, and no problems should be caused on the way.

Chapter 4 - Diagnosis of COVID-19

The diagnosis of COVID-19 is based on epidemiological history, clinical manifestations, and pathogenic confirmation.

Chapter 3 - Clinical features of COVID-19

The incubation period from exposure to symptoms is generally 7–14 days;the shortest is 1 day, the longest is up to 20 days. Fever, fatigue, and dry cough appear to be the most common symptoms at illness onset, but these symptoms, which also present in influenza and other respiratory infections, are nonspecific. Upper respiratory tract symptoms like nasal obstruction and rhinorrhea are relatively rare. In general, the majority of patients have a satisfactory prognosis with a few patients being critically ill. Fatal cases are commonly seen in the elderly and those with chronic underlying diseases, such as diabetes and heart disease.

Chapter 2 - Pathogenesis of COVID-19

Combined with clinical manifestations and chest imaging features, such as dry cough and abnormal coagulation function, chest imaging mainly showed multiple small patches and interstitial changes at the early stage, with obvious extravasation and less exudative lesions, which developed into multiple ground-glass opacity and infiltrating shadows in the lungs. In critically ill patients receiving tracheal intubation, infiltration fluid is rare in the trachea, which is different from influenza and avian influenza. We assume that pathogenesis of COVID-19 lung injury could mainly be impairment of the lung interstitium and vascular endothelium. Although ARDS can be found in some patients, exudative lesions are relatively less.

Chapter 1 - Respiratory virus and COVID-19

Viral infectious diseases remain a major challenge for human health. Following the emergence of a new coronavirus pneumonia, more than 10,000 species of wild viruses have been mentioned by mass media, but only a few are well recognized. In recent decades, human beings have constantly faced the challenge of bacterial and viral infections. The most common pathogens of new infectious diseases are viruses, the latest being COVID-19. Therefore, we should pay close attention to the severity of respiratory virus infection. There are many common viruses that can cause respiratory infections, including influenza-related viruses, human metapneumovirus, measles virus, rhinovirus, enterovirus, coronavirus, respiratory tract syncytial virus, adenovirus, cytomegalovirus, herpes simplex virus, etc. In particular, there are more than 100 species of coronaviruses.