A general urban spreading pattern of COVID-19 and its underlying mechanism

Currently, the global situation of COVID-19 is aggravating, pressingly calling for efficient control and prevention measures. Understanding the spreading pattern of COVID-19 has been widely recognized as a vital step for implementing non-pharmaceutical measures. Previous studies explained the differences in contagion rates due to the urban socio-political measures, while fine-grained geographic urban spreading pattern still remains an open issue. Here, we fill this gap by leveraging the trajectory data of 197,808 smartphone users (including 17,808 anonymous confirmed cases) in nine cities in China. We find a general spreading pattern in all cities: the spatial distribution of confirmed cases follows a power-law-like model and the spreading centroid human mobility is time-invariant. Moreover, we reveal that long average traveling distance results in a high growth rate of spreading radius and wide spatial diffusion of confirmed cases in the fine-grained geographic model. With such insight, we adopt the Kendall model to simulate the urban spreading of COVID-19 which can well fit the real spreading process. Our results unveil the underlying mechanism behind the spatial-temporal urban evolution of COVID-19, and can be used to evaluate the performance of mobility restriction policies implemented by many governments and to estimate the evolving spreading situation of COVID-19.

A general urban spreading pattern of COVID-19 and its underlying mechanism

Currently, the global situation of COVID-19 is aggravating, pressingly calling for efficient control and prevention measures. Understanding the spreading pattern of COVID-19 has been widely recognized as a vital step for implementing non-pharmaceutical measures. Previous studies explained the differences in contagion rates due to the urban socio-political measures, while fine-grained geographic urban spreading pattern still remains an open issue. Here, we fill this gap by leveraging the trajectory data of 197,808 smartphone users (including 17,808 anonymous confirmed cases) in nine cities in China. We find a general spreading pattern in all cities: the spatial distribution of confirmed cases follows a power-law-like model and the spreading centroid human mobility is time-invariant. Moreover, we reveal that long average traveling distance results in a high growth rate of spreading radius and wide spatial diffusion of confirmed cases in the fine-grained geographic model. With such insight, we adopt the Kendall model to simulate the urban spreading of COVID-19 which can well fit the real spreading process. Our results unveil the underlying mechanism behind the spatial-temporal urban evolution of COVID-19, and can be used to evaluate the performance of mobility restriction policies implemented by many governments and to estimate the evolving spreading situation of COVID-19.

Use of temporal contact graphs to understand the evolution of COVID-19 through contact tracing data.

Digital contact tracing has been recently advocated by China and many countries as part of digital prevention measures on COVID-19. Controversies have been raised about their effectiveness in practice as it remains open how they can be fully utilized to control COVID-19. In this article, we show that an abundance of information can be extracted from digital contact tracing for COVID-19 prevention and control. Specifically, we construct a temporal contact graph that quantifies the daily contacts between infectious and susceptible individuals by exploiting a large volume of location-related data contributed by 10,527,737 smartphone users in Wuhan, China. The temporal contact graph reveals five time-varying indicators can accurately capture actual contact trends at population level, demonstrating that travel restrictions (e.g., city lockdown) in Wuhan played an important role in containing COVID-19. We reveal a strong correlation between the contacts level and the epidemic size, and estimate several significant epidemiological parameters (e.g., serial interval). We also show that user participation rate exerts higher influence on situation evaluation than user upload rate does, indicating a sub-sampled dataset would be as good at prediction. At individual level, however, the temporal contact graph plays a limited role, since the behavior distinction between the infected and uninfected individuals are not substantial. The revealed results can tell the effectiveness of digital contact tracing against COVID-19, providing guidelines for governments to implement interventions using information technology.

Spatial–Temporal Urban Mobility Pattern Analysis During COVID-19 Pandemic

In response to the repeated outbreaks of the COVID-19, many countries implement the region-specific, multilevel epidemic prevention and control policies. To fully understand the impact of these interventions on urban mobility, it is urgent to analyze spatial-temporal mobility pattern at the neighborhood level and structural changes in urban mobility networks. Here, we construct urban mobility networks among points of interest (POIs), using large-scale anonymous mobility data from de-identified mobile phone users. We comprehensively investigate the changes of urban mobility networks during two waves of the COVID-19 pandemic in Beijing from both graph and subgraph perspectives. Beyond an overall mobility reduction in Beijing, we find that the mobility change is spatially and temporally heterogeneous among different urban regions. We uncover a disproportionately large reduction in long-distance, nighttime, and non-essential travel. This results in a more geographically fragmented, local, and regional network in the pandemic. We demonstrate that these structural changes slow down the spatial spread of the COVID-19 in the mobility network.

A highly powerful nonspecific strategy to reduce COVID-19 deaths.

The coronavirus disease 2019 (COVID-19) pandemic caused by the coronavirus severe acute respiratory syndrome coronavirus 2 remains risky worldwide. We elucidate here that good IDM (isolation, disinfection, and maintenance of health) is powerful to reduce COVID-19 deaths based on the striking differences in COVID-19 case fatality rates among various scenarios. IDM means keeping COVID-19 cases away from each other and from other people, disinfecting their living environments, and maintaining their health through good nutrition, rest, and treatment of symptoms and pre-existing diseases (not through specific antiviral therapy). Good IDM could reduce COVID-19 deaths by more than 85% in 2020 and more than 99% in 2022. This is consistent with the fact that good IDM can minimize co-infections and maintain body functions and the fact that COVID-19 has become less pathogenic (this fact was supported with three novel data in this report). Although IDM has been frequently implemented worldwide to some degree, IDM has not been highlighted sufficiently. Good IDM is relative, nonspecific, flexible, and feasible in many countries, and can reduce deaths of some other relatively mild infectious diseases. IDM, vaccines, and antivirals aid each other to reduce COVID-19 deaths. The IDM concept and strategy can aid people to improve their health behavior and fight against COVID-19 and future pandemics worldwide.

Phylogenetic and Spatiotemporal Analyses of the Complete Genome Sequences of Avian Coronavirus Infectious Bronchitis Virus in China During 1985-2020: Revealing Coexistence of Multiple Transmission Chains and the Origin of LX4-Type Virus.

Infectious bronchitis (IB) virus (IBV) causes considerable economic losses to poultry production. The data on transmission dynamics of IBV in China are limited. The complete genome sequences of 212 IBV isolates in China during 1985-2020 were analyzed as well as the characteristics of the phylogenetic tree, recombination events, dN/dS ratios, temporal dynamics, and phylogeographic relationships. The LX4 type (GI-19) was found to have the highest dN/dS ratios and has been the most dominant genotype since 1999, and the Taiwan-I type (GI-7) and New type (GVI-1) showed an increasing trend. A total of 59 recombinants were identified, multiple recombination events between the field and vaccine strains were found in 24 isolates, and the 4/91-type (GI-13) isolates were found to be more prone to being involved in the recombination. Bayesian phylogeographic analyses indicated that the Chinese IBVs originated from Liaoning province in the early 1900s. The LX4-type viruses were traced back to Liaoning province in the late 1950s and had multiple transmission routes in China and two major transmission routes in the world. Viral phylogeography identified three spread regions for IBVs (including LX4 type) in China: Northeastern China (Heilongjiang, Liaoning, and Jilin), north and central China (Beijing, Hebei, Shanxi, Shandong, and Jiangsu), and Southern China (Guangxi and Guangdong). Shandong has been the epidemiological center of IBVs (including LX4 type) in China. Overall, our study highlighted the reasons why the LX4-type viruses had become the dominant genotype and its origin and transmission routes, providing more targeted strategies for the prevention and control of IB in China.

Novel statistics predict the COVID-19 pandemic could terminate in 2022.

Many people want to know when the COVID-19 pandemic will end and life will return to normal. This question is highly elusive and distinct predictions have been proposed. In this study, the global mortality and case fatality rate of COVID-19 were analyzed using nonlinear regression. The analysis showed that the COVID-19 pandemic could terminate in 2022, but COVID-19 could be one or two times more deadly than seasonal influenza by 2023. The prediction considered the possibility of the emergence of new variants of SARS-CoV-2 and was supported by the features of the Omicron variant and other facts. As the herd immunity against COVID-19 established through natural infections and mass vaccination is distinct among countries, COVID-19 could be more or less deadly in some countries in the coming years than the prediction. Although the future of COVID-19 will have multiple possibilities, this statistics-based prediction could aid to make proper decisions and establish an example on the prediction of infectious diseases.

Should the world collaborate imminently to develop neglected live-attenuated vaccines for COVID-19?

The rapid spread of the Delta variant suggests that SARS-CoV-2 will likely be rampant for months or years and could claim millions of more lives. All the known vaccines cannot well defeat SARS-CoV-2 due to their limited efficacy and production efficiency, except for the neglected live-attenuated vaccines (LAVs), which could have a much higher efficacy and much higher production efficiency than other vaccines. LAVs, like messiahs, have defeated far more pathogenic viruses than other vaccines in history, and most current human vaccines for viral diseases are safe LAVs. LAVs can block completely infection and transmission of relevant viruses and their variants. They can hence inhibit the emergence of vaccine-escape and virulence-enhancing variants and protect immunologically abnormal individuals better in general. The safety of COVID-19 LAVs, which could save millions of more lives, can be solidly guaranteed through animal experiments and clinical trials. The safety of COVID-19 LAVs could be greatly enhanced with intramuscular or oral administration, or administration along with humanized neutralizing monoclonal antibodies. Together, extensive global collaboration, which can greatly accelerate the development of safe COVID-19 LAVs, is imminently needed.

Exploring the Effects of Carpooling on Travelers’ Behavior during the COVID-19 Pandemic: A Case Study of Metropolitan City

Transportation accounts for more than a quarter of the greenhouse gas emissions that are causing climate change. Carpooling is a subset of the sharing economy, in which individuals share their vehicle with commuters to save travel expenses. In recent decades, carpooling has been promoted as a feasible alternative to car ownership with the potential to alleviate traffic congestion, parking demand, and environmental problems. Unstable economic conditions, cultural norms, and lack of infrastructure make cultural exchange activities and mobility habits different in developing nations to those in developed countries. The rapid evolution of sharing mobility has reshaped travelers’ behavior and created a dire need to determine the travel patterns of commuters living in megacities in developing countries. To obtain data, a web-based stated choice (SC) experiment was used in this study. It used mode-related variables, socioeconomic demographic variables, and a coronavirus disease 2019 (COVID-19) precautionary measure variable. Logit models, namely the mixed logit regression model (ML) and the multinomial logit regression model (MNL), were applied to analyze the available data. According to modeling and survey data, economic variables associated with modes of transport, such as trip time and trip cost, were determined to be significant. Additionally, the results revealed that commuters were more conscious of COVID-19 preventive measures, which was determined to be highly significant. The findings showed that the majority of residents in the COVID-19 pandemic continue to rely on automobiles and motorcycles. It is noteworthy that individuals with more than two members in their family and a travel distance of less than seven miles were more likely to prefer a carpooling service. This study’s findings will provide a basis for researchers to aid existing operators in the field of transportation, as well as offer guidelines for governments in developing countries to enhance the utility of transportation networks.

Live unattenuated vaccines for controlling viral diseases, including COVID-19.

Live unattenuated vaccines (LUVs) have been neglected for decades, due to widespread prejudice against their safety, even though they have successfully controlled yellow fever and adenovirus infection in humans as well as rinderpest and infectious bursal disease in animals. This review elucidated that LUVs could be highly safe with selective use of neutralizing antivirus antibodies, natural antiglycan antibodies, nonantibody antivirals, and ectopic inoculation. Also, LUVs could be of high efficacy, high development speed, and high production efficiency, with the development of humanized monoclonal antibodies and other modern technologies. They could circumvent antibody-dependent enhancement and maternal-derived antibody interference. With these important advantages, LUVs could be more powerful than other vaccines for controlling some viral diseases, and they warrant urgent investigation with animal experiments and clinical trials for defeating the COVID-19 pandemic caused by the novel coronavirus SARS-CoV-2.

SARS-CoV-2 replicating in nonprimate mammalian cells probably have critical advantages for COVID-19 vaccines due to anti-Gal antibodies: A minireview and proposals.

Glycoproteins of enveloped viruses replicating in nonprimate mammalian cells carry α-1,3-galactose (α-Gal) glycans, and can bind to anti-Gal antibodies which are abundant in humans. The antibodies have protected humans and their ancestors for millions of years, because they inhibit replication of many kinds of microbes carrying αGal glycans and aid complements and macrophages to destroy them. Therefore, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replicating in nonprimate mammalian cells (eg, PK-15 cells) carry αGal glycans and could be employed as a live vaccine for corona virus 2019 (COVID-19). The live vaccine safety could be further enhanced through intramuscular inoculation to bypass the fragile lungs, like the live unattenuated adenovirus vaccine safely used in US recruits for decades. Moreover, the immune complexes of SARS-CoV-2 and anti-Gal antibodies could enhance the efficacy of COVID-19 vaccines, live or inactivated, carrying α-Gal glycans. Experiments are imperatively desired to examine these novel vaccine strategies which probably have the critical advantages for defeating the pandemic of COVID-19 and preventing other viral infectious diseases.

Potential for elimination of SAR-CoV-2 through vaccination as inspired by elimination of multiple influenza viruses through natural pandemics or mass vaccination.

The ongoing pandemic of coronavirus disease 2019 (COVID-19) caused by the novel virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has claimed many lives worldwide. To combat the pandemic, multiple types of vaccines are under development with unprecedented rapidity. Theoretically, future vaccination against COVID-19 may fall into long-term costly guerrilla warfare between SARS-CoV-2 and humans. Elimination of SARS-CoV-2 through vaccination to avoid the potential long-term costly guerrilla warfare, if possible, is highly desired and worth intensive consideration. Human influenza pandemics emerging in 1957, 1968, and 2009 established strong global herd immunity and led to the elimination of three human influenza viruses, which circulated worldwide for years before the pandemics. Moreover, both clade 7.2 of subtype H5 highly pathogenic avian influenza virus and subtype H7N9 avian influenza virus circulated in poultry in China for years, and they have been virtually eliminated through mass vaccination in recent years. These facts suggest that the rapid establishment of global herd immunity through mass vaccination using an appropriate vaccine could eliminate SARS-CoV-2. The coming 2 years are a golden time for elimination through vaccination, which requires tremendous national and international collaboration. This review also prioritizes the efficacy of vaccines for COVID-19 and elucidates the importance of the development of more live vaccines for COVID-19.

Decontamination of face masks with steam for mask reuse in fighting the pandemic COVID-19: Experimental supports.

The coronavirus disease 2019 pandemic caused by the novel coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) has claimed many lives worldwide. Wearing medical masks (MMs) or N95 masks ([N95Ms] namely N95 respirators) can slow the virus spread and reduce the infection risk. Reuse of these masks can minimize waste, protect the environment, and help solve the current imminent shortage of masks. Disinfection of used masks is needed for their reuse with safety, but improper decontamination can damage the blocking structure of masks. In this study, we demonstrated using the avian coronavirus of infectious bronchitis virus to mimic SARS-CoV-2 that MMs and N95Ms retained their blocking efficacy even after being steamed on boiling water for 2 hours. We also demonstrated that three brands of MMs blocked over 99% viruses in aerosols. The avian coronavirus was completely inactivated after being steamed for 5 minutes. Altogether, this study suggested that MMs are adequate for use on most social occasions and both MMs and N95Ms can be reused for a few days with steam decontamination between use.

Potential of live pathogen vaccines for defeating the COVID-19 pandemic: History and mechanism.

The whole world has entered a terrible crisis with a huge and increasing number of human deaths and economic losses in fighting the pandemic of COVID-19 caused by the novel coronavirus termed SARS-CoV-2. The live pathogen vaccine (LPV) strategy, which originated in ancient China for fighting smallpox, has been applied successfully by US military recruits for decades to control acute respiratory diseases caused by types 4 and 7 adenoviruses. This strategy has also been widely employed in veterinary medicine. These facts suggest a fast way out of the current pandemic crisis, namely that SARS-CoV-2 could be directly used as a live vaccine. Beyond the two traditional mechanisms to guarantee the LPV's safety (the LPV seed strain is properly selected; the LPV is inoculated bypassing the respiratory sites of pathology), three novel mechanisms to further ensure the LPV's safety are available (the virus replication is inhibited with early use of an antiviral drug; symptomatic LPV recipients are cured with convalescent plasma; the LPV is inoculated in the hot season). This LPV strategy has multiple potential advantages over other options and could reduce morbidity and mortality greatly as well as the economic loss caused by the pandemic. The safety and efficacy of this strategy should be investigated strictly using animal experiments and clinical trials, and even if the experiments and trials all support the strategy, it should be implemented with enough caution.