Efficacy of umbilical cord mesenchymal stromal cells for COVID-19: A systematic review and meta-analysis.

Objectives: A major challenge for COVID-19 therapy is dysregulated immune response associated with the disease. Umbilical cord mesenchymal stromal cells (UC-MSCs) may be a promising candidate for COVID-19 treatment owing to their immunomodulatory and anti-inflammatory functions. Therefore, this study aimed to evaluate the effectiveness of UC-MSCs inpatients with COVID-19. Method: Medline, Embase, PubMed, Cochrane Library, and Web of Science databases were searched to collect clinical trials concerning UC-MSCs for the treatment of COVID-19. After literature screening, quality assessment, and data extraction, a systematic review and meta-analysis of the included study were performed. Results: This systematic review and meta-analysis were prospectively registered on PROSPERO, and the registration number is CRD42022304061. After screening, 10 studies involving 293 patients with COVID-19 were eventually included. Our meta-analysis results showed that UC-MSCs can reduce mortality (relative risk [RR] =0.60, 95% confidence interval [CI]: [0.38, 0.95], P=0.03) in COVID-19 patients. No significant correlation was observed between adverse events and UC-MSC treatment (RR=0.85, 95% CI: [0.65, 1.10], P=0.22; RR=1.00, 95%CI: [0.64, 1.58], P=1.00). In addition, treatment with UC-MSCs was found to suppress inflammation and improve pulmonary symptoms. Conclusions: UC-MSCs hold promise as a safe and effective treatment for COVID-19. Systematic Review Registartion: PROSPERO, identifier CRD42022304061.

Assessing vaccination priorities for different ages and age-specific vaccination strategies of COVID-19 using an SEIR modelling approach.

In the past year, the global epidemic situation is still not optimistic, showing a trend of continuous expansion. With the research and application of vaccines, there is an urgent need to develop some optimal vaccination strategies. How to make a reasonable vaccination strategy to determine the priority of vaccination under the limited vaccine resources to control the epidemic and reduce human casualties? We build a dynamic model with vaccination which is extended the classical SEIR model. By fitting the epidemic data of three countries-China, Brazil, Indonesia, we have evaluated age-specific vaccination strategy for the number of infections and deaths. Furthermore, we have evaluated the impact of age-specific vaccination strategies on the number of the basic reproduction number. At last, we also have evaluated the different age structure of the vaccination priority. It shows that giving priority to vaccination of young people can control the number of infections, while giving priority to vaccination of the elderly can greatly reduce the number of deaths in most cases. Furthermore, we have found that young people should be mainly vaccinated to reduce the number of infections. When the emphasis is on reducing the number of deaths, it is important to focus vaccination on the elderly. Simulations suggest that appropriate age-specific vaccination strategies can effectively control the epidemic, both in terms of the number of infections and deaths.

Modeling and analysis of COVID-19 based on a time delay dynamic model.

The new type of coronavirus pneumonia is caused by the new type of coronavirus which appeared at the end of 2019. Because of its strong contagiousness, rapid spread and great harm, it has already given countries around the world serious effects. So far there is no clear specific drug. Scientifically grasping the development law of epidemics is extremely important for preventing and controlling epidemics. Since the latent of this epidemic are also highly contagious, traditional infectious disease models cannot accurately describe the regularity of this epidemic transmission. Based on the traditional infectious disease model, an infectious disease model with a time delay is proposed. The time difference is used to characterize the cycle of viral infection and treatment time. Using the epidemic data released in real time, firstly, through the numerical simulation parameter inversion, the minimum error is obtained; then we simulate the development trend of the epidemic according to the dynamics system; finally, we compare and analyze the effectiveness of isolation measures. This article has simulated COVID-19 and analyzed the development of the epidemic in Beijing and Wuhan. By comparing the severity of the epidemic in the two regions, early detection and isolation are still the top priority of epidemic prevention and control.