This article reviews the correlation between angiotensin‐converting enzyme 2 (ACE2) and severe risk factors for coronavirus disease 2019 (COVID‐19) and the possible mechanisms. ACE2 is a crucial component of the renin‐angiotensin system (RAS). The classical RAS ACE‐Ang II‐AT1R regulatory axis and the ACE2‐Ang 1‐7‐MasR counter‐regulatory axis play an essential role in maintaining homeostasis in humans. ACE2 is widely distributed in the heart, kidneys, lungs, and testes. ACE2 antagonizes the activation of the classical RAS system and protects against organ damage, protecting against hypertension, diabetes, and cardiovascular disease. Similar to SARS‐CoV, SARS‐CoV‐2 also uses the ACE2 receptor to invade human alveolar epithelial cells. Acute respiratory distress syndrome (ARDS) is a clinical high‐mortality disease, and ACE2 has a protective effect on this type of acute lung injury. Current research shows that the poor prognosis of patients with COVID‐19 is related to factors such as sex (male), age (>60 years), underlying diseases (hypertension, diabetes, and cardiovascular disease), secondary ARDS, and other relevant factors. Because of these protective effects of ACE2 on chronic underlying diseases and ARDS, the development of spike protein‐based vaccine and drugs enhancing ACE2 activity may become one of the most promising approaches for the treatment of COVID‐19 in the future.

In the past few decades, coronaviruses have risen as a global threat to public health. Currently, the outbreak of coronavirus disease‐19 (COVID‐19) from Wuhan caused a worldwide panic. There are no specific antiviral therapies for COVID‐19. However, there are agents that were used during the severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) epidemics. We could learn from SARS and MERS. Lopinavir (LPV) is an effective agent that inhibits the protease activity of coronavirus. In this review, we discuss the literature on the efficacy of LPV in vitro and in vivo, especially in patients with SARS and MERS, so that we might clarify the potential for the use of LPV in patients with COVID‐19.

Infectious diseases and antimicrobial resistance (AMR) has become pressing concerns in China. We aimed to comprehensively investigate the burden of them. Data on infectious diseases and AMR were collected by the Global Antimicrobial Resistance Burden study 2019. Multinomial network meta-regression, logistic regression, and ensemble Spatiotemporal Gaussian process regression were used to fit the number and rate in DisMod-MR 2.1 modelling framework. We reported the number and rates of the disease burdens of 12 infectious syndromes by age and sex; described the burden caused by 43 pathogens; estimated the AMR burden of 22 bacteria and bacteria–antibiotics combinations. There were an estimated 1.3 million (95% uncertainty intervals, UI 0.8–1.9) infection-related deaths, accounting for 12.1% of the total deaths in China 2019. Males were 1.5 times more affected than females. Bloodstream infections (BSIs) were most lethal infectious syndrome, associating with 521,392 deaths (286,307–870,583), followed by lower respiratory infections (373,175), and peritoneal and intra-abdominal infections (152,087). These five leading pathogens were S aureus, A baumannii, E coli, S pneumoniae, and E spp., which were associated with 41.2% (502,658/1,218,693) of all infection-related deaths. The pathogens of different infectious syndromes exhibited significant heterogeneity. In 2019, more than 600 thousand deaths were associated with AMR, including 145 thousand deaths attributable to AMR. The top 3 AMR attributable to death were carbapenems-resistance A baumannii (18,143), methicillin-resistance S aureus (16,933) and third-generation cephalosporins-resistance E coli (8032). Infectious diseases and bacterial antimicrobial resistance were serious threat to public health in China, related to 1.3 million and more than 600 thousand deaths per-year, respectively. Antimicrobial stewardship was urgent. This work was supported by 10.13039/501100001809 National Natural Science Foundation of China (82270626); China Mega-Project for Infectious Diseases (2017ZX10203202, 2013ZX10002005); the Project of Beijing Science and Technology Committee (Z191100007619037).

Since December 2019, COVID-19 has spread to almost every corner of the world. In theory, tocilizumab and favipiravir are considered to be reliable drugs for the treatment of COVID-19 with elevated IL-6. We aimed to assess the efficacy and safety of tocilizumab combined with favipiravir in patients with COVID-19. This was a multicenter trial in adults with COVID-19. Patients were randomly assigned (3:1:1) to a 14-day combination of favipiravir combined with tocilizumab (combination group), favipiravir, and tocilizumab. The primary outcome was the cumulative lung lesion remission rate (lung CT examination indicated absorption of lung inflammation). Between Feb 2 and March 15, 2020, 26 patients were recruited; 14 were randomly assigned to the combination group, 7 were assigned to the favipiravir group and 5 were assigned to the tocilizumab group. The cumulative lung lesion remission rate at day 14 was significantly higher in combination group as compared with favipiravir group (P = 0.019, HR 2.66 95 % CI [1.08–6.53]). And there was also a significant difference between tocilizumab and favipivavir (P = 0.034, HR 3.16, 95 % CI 0.62–16.10). In addition, there was no significant difference between the combination group and the tocilizumab group (P = 0.575, HR 1.28 95 %CI 0.39–4.23). Furthermore, combined therapy can also significantly relieve clinical symptoms and help blood routine to return to normal. No serious adverse events were reported. Tocilizumab combined with or without favipiravir can effectively improve the pulmonary inflammation of COVID-19 patients and inhibit the deterioration of the disease.