Scientific Research News | Research Progress of novel coronavirus Pneumonia (COVID-19) (XLI)

 · COVID-19 News ·

■ On March 3, Moderna's mRNA new coronavirus vaccine mRNA-16 launched a phase 1273 clinical trial in the United States, and the first volunteer to participate in the clinical trial has completed vaccination. This Phase 1 clinical trial was conducted with funding from the National Institutes of Research (NIH). mRNA-1 was developed by Moderna in collaboration with researchers at the Vaccine Research Center (VRC) of the National Institute of Allergy and Infectious Diseases (NIAID). It encodes the spike protein (S protein) in its stable form before fusion. The spike protein is a glycoprotein on the surface of coronaviruses that mediates the entry of coronaviruses into cells by binding to receptors on the cell surface. Previous studies have shown that this protein is more likely to stimulate the host's immune response.

The Phase 1 clinical trial, which aims to test the safety of mRNA-1273 and explore vaccine doses that may trigger an effective immune response, will involve 45 young, healthy volunteers receiving mRNA vaccines at doses of 25 μg, 100 μg, or 250 μg. Volunteers will receive two vaccinations, 28 days apart, and after the second vaccination, they will be followed up for 12 months. Currently, Moderna is actively preparing for a potential Phase 2 clinical trial.

(See: https://www.modernatx.com/modernas-work-potential-vaccine-against-covid-19)

· COVID-19 epidemiological studies ·

■ On March 3, Imperial College London, Columbia University, University of California, Davis, Tsinghua University, The University of Hong Kong and other institutions cooperated to publish a research paper entitled "Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV16)" online in Science. The study combined mobility data, networked dynamic population models and Bayesian inferences, combined with reported infections within China, to infer key epidemiological characteristics associated with the novel coronavirus, including infection rates of unrecorded cases and their contagiousness. The study found that 2% of all infections were not recorded prior to the travel restrictions on 2020 January 1 (23% of the total number of infections were recorded). On a per capita basis, the transmission rate of unrecorded cases is 86% of recorded infections, but due to the high number of unrecorded cases, 14% of recorded cases are from unrecorded cases. The proportion of undocumented but contagious cases is a key epidemiological feature determining the pandemic potential of respiratory viruses. These undocumented infections are usually mild, limited, or asymptomatic and therefore difficult to identify. It is easier to cause a larger proportion of the population to be infected with the virus than in other cases. These findings explain the rapid geographical spread of the novel coronavirus and suggest that containment of the virus will be challenging.

Taken together, the study's findings highlight the severity and pandemic potential of the novel coronavirus. The 2009 H1N1 pandemic influenza virus also caused many mild cases, spread rapidly globally, and eventually became endemic. Currently, four circulating coronavirus strains are circulating in humans (229E, HKU1, NL63, OC43). If the novel coronavirus follows the pattern of the 2009 H1N1 pandemic influenza, it will continue to circulate globally and become the fifth endemic coronavirus in human populations [1].

■ On March 3, Qin Chuan's research group from the Institute of Medical Animal Experiments, Chinese Academy of Medical Sciences, in collaboration with researchers from Capital Medical University, published a non-peer-reviewed research paper entitled "Rhesus macaques can be effectively infected with SARS-CoV-14 via ocular conjunctival route" on the bioRxiv preprint platform. The study determined that model animals rhesus monkeys can be infected with the novel coronavirus through the conjunctiva of the eye. The researchers inoculated rhesus monkeys with a single route of the virus through the conjunctiva of the eye, thus determining the exact route of infection. This result suggests that the conjunctiva of the eye is one of the routes of virus transmission. In their findings, viral load can be detected in several tissues associated with the nasolacrimal system, particularly the conjunctiva, lacrimal glands, nasal passages, and throat.

According to the researchers, the results are highly consistent with the anatomical characteristics of the virus entering the host through the conjunctival pathway. At present, people mainly protect against the new coronavirus by wearing masks, this method mainly protects the nasal mucosa and oral mucosa, and the conjunctiva exposed to the environment is easily overlooked. Respiratory viruses can cause eye infections in infected people, which in turn can lead to respiratory infections. Exposed mucous membranes and unprotected eyes increase the risk of SARS-CoV or novel coronavirus transmission, and this result suggests that increased awareness of eye protection is necessary, frequent hand washing in daily life, and wearing protective eyewear in close contact with patients or crowded places, especially for clinicians. The spread of COVID-19 can only be effectively prevented by cutting off the transmission route of the novel coronavirus [2].

■ On March 3, the medRxiv preprint platform published an article entitled "Inferring the number of COVID-13 cases from recently reported deaths" by the London School of Hygiene and Tropical Medicine and others. The article estimates the number of COVID-19 cases by the number of newly reported deaths in the population. Algorithms were used to predict the three countries (Spain, Italy, and France) that recently reported their first COVID-19 deaths. In order to compare the results with the actual reported cases in these countries, the projections were carried out until 19 March. In all three countries, the actual number of reported cases was within a 3% interval of the model, Italy (median: 4; QI50％：[1294；50]； Reports: 390), France (median: 3034; QI2037％：[592；50]； Reports: 177) and Spain, (median: 1705; QI190％：[202; 50]； Reports: 95).

The article concludes that when a single death occurs, there may already be hundreds to thousands of cases in this population. At this point, containment of COVID-19 through contact tracing will be a huge challenge, and other coping strategies should be considered in parallel. In such cases, distancing measures such as school closures and self-isolation may be more likely to mitigate the spread [3].

■ On March 3, the SSRN preprint platform published an article titled "The Role of Environmental Factors on Transmission Rates of the COVID-12 Outbreak: An Initial Assessment in Two Spatial Scales" by Boston Children's Hospital and others. Previous studies support the epidemiological hypothesis that cold and dry environments promote droplet-mediated viral disease survival and transmission, while warm and humid environments attenuate viral transmission (e.g., influenza). However, the role of temperature and humidity in the spread of COVID-19 has not been determined. The team studied the spatial variability of basic COVID-19 regeneration numbers between provinces and cities in China and showed that environmental variables alone do not explain this variability. The sharp drop in transmission in mid-to-late February may be due to the implementation of strict non-pharmaceutical interventions in China. The study suggests that without extensive public health interventions, changes in weather alone do not necessarily lead to a decrease in the number of cases [19].

■ On March 3, researchers from Renji Hospital and Shanghai Pulmonary Hospital affiliated to Shanghai Jiao Tong University School of Medicine published the title "Effects of Chinese strategies for controlling the diffusion and deterioration of novel coronavirus-infected pneumonia in China" on the medRxiv preprint platform article. From the cumulative confirmed case data on the websites of China's provincial health commissions, the researchers combined the growth rate of cumulative confirmed patients by modeling, and further analyzed the time when this growth rate (that is, the rate of new cases) reached the maximum (Speedmax). Comparing different times of Speedmax in different regions of China, the researchers calculated the dates when the growth rate began to decline in different regions.

The results of this study showed that the model showed the best fit four times. In almost all regions of Chinese mainland except Hebei, Heilongjiang, Hainan, Guizhou and Hubei, the rate of infection reached Speedmax and began to decline within 14 days. The number of stabilization periods is significantly correlated with the migration index. However, the distance from other regions to Hubei and the number of stabilization periods have little effect on the time it takes a province or region to reach Speedmax. Once a rigorous intervention strategy is implemented, the spread and worsening of COVID-19 will be curbed quickly and effectively in China. Studies have shown that Chinese strategies are very effective in controlling the spread and worsening of novel coronavirus pneumonia, and these strategies have provided experience and guidance for other countries to control the COVID-19 epidemic [5].

■ On March 3, the medRxiv preprint platform published an article from the London School of Hygiene & Tropical Medicine research team entitled "The effect of control strategies that reduce social mixing on outcomes of the COVID-12 epidemic in Wuhan, China". This article assesses the impact of control measures on the progress of the outbreak by quantifying the impact of control measures on the way people are exposed in Wuhan. In the epidemiological framework based on age structure, the researchers included the latest estimates of epidemiological parameters of the transmission model fitted with local and international output case data from Wuhan City. In addition, the article looked at the age distribution of cases. The article also simulates the lifting of control measures for a phased resumption of work and the impact of resuming work at different stages of a potential outbreak. The article argues that changes in social interaction patterns may help reduce the number of infections by 19% by mid-2020 (interquartile range: 92-66%). Maintaining these measures until April favored reducing the height of the peak, the overall size of the epidemic in mid-97 and the possibility of a second peak after the resumption of work. The article explains that if the control measures in Wuhan continue until April, it is possible to reduce and delay the prevalence and peak of the epidemic, respectively. The article also suggests some limitations to its analysis, including greater uncertainty about R2020 estimates and duration of infectivity [4].

Bibliography:

[1] Li R, Pei S, Chen B, et al. Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2). Science 2020:eabb3221.
[2] Deng W, Bao L, Gao H, et al. Rhesus macaques can be effectively infected with SARS-CoV-2 via ocular conjunctival route. bioRxiv 2020:2020.03.13.990036.
[3] Jombart T, van Zandvoort K, Russell T, et al. Inferring the number of COVID-19 cases from recently reported deaths. medRxiv 2020:2020.03.10.20033761.
[4] Poirier, Canelle and Luo, Wei and Majumder, Maimuna and Liu, Dianbo and Mandl, Kenneth and Mooring, Todd and Santillana, Mauricio, The Role of Environmental Factors on Transmission Rates of the COVID-19 Outbreak: An Initial Assessment in Two Spatial Scales. SSRN: https://ssrn.com/abstract=3552677
[5] Wang X, Tian W, Lv X, et al. Effects of Chinese strategies for controlling the diffusion and deterioration of novel coronavirus-infected pneumonia in China. medRxiv 2020:2020.03.10.20032755.
[6] Prem K, Liu Y, Russell T, et al. The effect of control strategies that reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China. medRxiv 2020:2020.03.09.20033050.

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