Evaluating the Demand for Nucleic Acid Testing in Different Scenarios of COVID-19 Transmission: A Simulation Study

INTRODUCTION

The 2019 novel coronavirus (COVID-19) has been recognized as the most severe human infectious disease pandemic in the past century. To enhance our ability to control potential infectious diseases in the future, this study simulated the influence of nucleic acid testing on the transmission of COVID-19 across varied scenarios. Additionally, it assessed the demand for nucleic acid testing under different circumstances, aiming to furnish a decision-making foundation for the implementation of nucleic acid screening measures, the provision of emergency materials, and the allocation of human resources.

METHODS

Considering the transmission dynamics of COVID-19 and the preventive measures implemented by countries, we explored three distinct levels of epidemic intensity: community transmission, outbreak, and sporadic cases. Integrating the theory of scenario analysis, we formulated six hypothetical epidemic scenarios, each corresponding to possible occurrences during different phases of the pandemic. We developed an improved SEIR model, validated its accuracy using real-world data, and conducted a comprehensive analysis and prediction of COVID-19 infections under these six scenarios. Simultaneously, we assessed the testing resource requirements associated with each scenario.

RESULTS

We compared the predicted number of infections simulated by the modified SEIR model with the actual reported cases in Israel to validate the model. The root mean square error (RMSE) was 350.09, and the R-squared (R2) was 0.99, indicating a well-fitted model. Scenario 4 demonstrated the most effective prevention and control outcomes. Strengthening non-pharmaceutical interventions and increasing nucleic acid testing frequency, even under low testing capacity, resulted in a delayed epidemic peak by 78 days. The proportion of undetected cases decreased from 77.83% to 31.21%, and the overall testing demand significantly decreased, meeting maximum demand even with low testing capacity. The initiation of testing influenced case detection probability. Under high testing capacity, increasing testing frequency elevated the detection rate from 36.40% to 77.83%. Nucleic acid screening proved effective in reducing the demand for testing resources under diverse epidemic prevention and control strategies. While effective interventions and nucleic acid screening measures substantially diminished the demand for testing-related resources, varying degrees of insufficient testing capacity may still persist.

CONCLUSIONS

The nucleic acid detection strategy proves effective in promptly identifying and isolating infected individuals, thereby mitigating the infection peak and extending the time to peak. In situations with constrained testing capacity, implementing more stringent measures can notably decrease the number of infections and alleviate resource demands. The improved SEIR model demonstrates proficiency in predicting both reported and unreported cases, offering valuable insights for future infection risk assessments. Rapid evaluations of testing requirements across diverse scenarios can aptly address resource limitations in specific regions, offering substantial evidence for the formulation of future infectious disease testing strategies.

Optimal resource allocation model for COVID-19: a systematic review and meta-analysis

BACKGROUND

A lack of health resources is a common problem after the outbreak of infectious diseases, and resource optimization is an important means to solve the lack of prevention and control capacity caused by resource constraints. This study systematically evaluated the similarities and differences in the application of coronavirus disease (COVID-19) resource allocation models and analyzed the effects of different optimal resource allocations on epidemic control.

METHODS

A systematic literature search was conducted of CNKI, WanFang, VIP, CBD, PubMed, Web of Science, Scopus and Embase for articles published from January 1, 2019, through November 23, 2023. Two reviewers independently evaluated the quality of the included studies, extracted and cross-checked the data. Moreover, publication bias and sensitivity analysis were evaluated.

RESULTS

A total of 22 articles were included for systematic review; in the application of optimal allocation models, 59.09% of the studies used propagation dynamics models to simulate the allocation of various resources, and some scholars also used mathematical optimization functions (36.36%) and machine learning algorithms (31.82%) to solve the problem of resource allocation; the results of the systematic review show that differential equation modeling was more considered when testing resources optimization, the optimization function or machine learning algorithm were mostly used to optimize the bed resources; the meta-analysis results showed that the epidemic trend was obviously effectively controlled through the optimal allocation of resources, and the average control efficiency was 0.38(95%CI 0.25-0.51); Subgroup analysis revealed that the average control efficiency from high to low was health specialists 0.48(95%CI 0.37-0.59), vaccines 0.47(95%CI 0.11-0.82), testing 0.38(95%CI 0.19-0.57), personal protective equipment (PPE) 0.38(95%CI 0.06-0.70), beds 0.34(95%CI 0.14-0.53), medicines and equipment for treatment 0.32(95%CI 0.12-0.51); Funnel plots and Egger's test showed no publication bias, and sensitivity analysis suggested robust results.

CONCLUSION

When the data are insufficient and the simulation time is short, the researchers mostly use the constructor for research; When the data are relatively sufficient and the simulation time is long, researchers choose differential equations or machine learning algorithms for research. In addition, our study showed that control efficiency is an important indicator to evaluate the effectiveness of epidemic prevention and control. Through the optimization of medical staff and vaccine allocation, greater prevention and control effects can be achieved.

Effect of Nucleic Acid Screening Measures on COVID-19 Transmission in Cities of Different Scales and Assessment of Related Testing Resource Demands-Evidence from China

BACKGROUND

COVID-19 is in its epidemic period, and China is still facing the dual risks of import and domestic rebound. To better control the COVID-19 pandemic under the existing conditions, the focus of this study is to simulate the nucleic acid testing for different population size cities in China to influence the spread of COVID-19, assess the situation under different scenarios, the demand for the laboratory testing personnel, material resources, for the implementation of the nucleic acid screening measures, emergency supplies, and the configuration of human resources to provide decision-making basis.

METHODS

According to the transmission characteristics of COVID-19 and the current prevention and control strategies in China, four epidemic scenarios were assumed. Based on the constructed SVEAI_iQHR model, the number of people infected with COVID-19 in cities with populations of 10 million, 5 million, and 500,000 was analyzed and predicted under the four scenarios, and the demand for laboratory testing resources was evaluated, respectively.

RESULTS

For large, medium, and small cities, whether full or regional nucleic acid screening can significantly reduce the epidemic prevention and control strategy of different scenarios laboratory testing resource demand difference is bigger, implement effective non-pharmaceutical interventions and regional nucleic acid screening measures to significantly reduce laboratory testing related resources demand, but will cause varying degrees of inspection staff shortages.

CONCLUSION

There is still an urgent need for laboratory testing manpower in China to implement effective nucleic acid screening measures in the event of an outbreak. Cities or regions with different population sizes and levels of medical resources should flexibly implement prevention and control measures according to specific conditions after the outbreak, assess laboratory testing and human resource need as soon as possible, and prepare and allocate materials and personnel.

Lutein alleviates arsenic-induced reproductive toxicity in male mice via Nrf2 signaling

This study aims to investigate the mechanisms involved in the action of lutein (LU) alleviating arsenic-induced reproductive toxicity using mice model. Forty male Kunming mice were received following treatments by gavage: normal saline solution (control), arsenic trioxide (ATO; 5 mg/kg/day), LU (40 mg/kg/day), and ATO + LU (5 mg/kg/day + 40 mg/kg/day). At the end, the mice were killed by cervical dislocation and weighed. Pathological examination was done on the testis. The biomedical parameters including superoxide dismutase (SOD), glutathione (GSH), total antioxidative capability, malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), and reproductive indexes were analyzed. The messenger RNA (mRNA) and protein expression of Nrf2, heme oxygenase 1 (HO-1), glutathione S-transferase (GST), nicotinamide adenine dinucleotide phosphate dehydrogenase, quinone 1 (NQO1) in testis were detected by real-time polymerase chain reaction and Western blot. We found that there was a decrease in sperm count; testis somatic index; the activities of SOD, GSH, total antioxidative capacity ( p < 0.01, respectively) in ATO-treated mice, while there was an increase in the levels of sperm abnormalities, MDA, and 8-OHdG than control ( p < 0.01, respectively). The groups treated with ATO + LU showed recovery of the measured parameters between those of ATO or saline-treated group. The antagonized interaction between ATO and LU was statistically significant ( p < 0.01). Mice treated with ATO + LU also showed greater mRNA expression of Nrf2, HO-1, NQO1, and GST than ATO or saline-treated groups. These findings suggest that LU alleviates reproductive toxicity induced by arsenic in male mice via Nrf2 signaling, which implicates a possible mechanism of LU in preventing the reproductive injury, and elucidates that consuming the rich plant sources of LU will alleviate the reproductive toxicity induced by chemicals.

Implementing a cervical cancer awareness program in low- income settings in Western China: a community-based locally affordable intervention for risk reduction

BACKGROUND

Some 60 years after introduction of the Papanicolaou smear worldwide, cervical cancer remains a burden in developing countries where >85% of world new cases and deaths occur, suggesting a failure to establish comprehensive cervical-cancer control programs. Effective interventions are available to control cervical cancer but are not all affordable in low-income settings. Disease awareness saves lives by risk-reduction as witnessed in reducing mortality of HIV/AIDS and smoking-related cancers.

SUBJECTS AND METHODS

We initiated a community-based awareness program on cervical cancer in two low-income Muslim Uyghur townships in Kashi (Kashgar) Prefecture, Xinjiang, China in 2008. The education involved more than 5,000 women from two rural townships and awareness was then evaluated in 2010 and 2011, respectively, using a questionnaire with 10 basic knowledge questions on cervical cancer. Demographic information was also collected and included in an EpiData database. A 10-point scoring system was used to score the awareness.

RESULTS

The effectiveness and feasibility of the program were evaluated among 4,475 women aged 19-70 years, of whom >92% lived on/ below US$1.00/day. Women without prior education showed a poor average awareness rate of 6.4% (164/2,559). A onetime education intervention, however, sharply raised the awareness rate by 4-fold to 25.5% (493/1,916). Importantly, low income and illiteracy were two reliable factors affecting awareness before or after education intervention.

CONCLUSIONS

Education intervention can significantly raise the awareness of cervical cancer in low-income women. Economic development and compulsory education are two important solutions in raising general disease awareness. We propose that implementing community-based awareness programs against cervical cancer is realistic, locally affordable and sustainable in low-income countries, which may save many lives over time and, importantly, will facilitate the integration of comprehensive programs when feasible. In this context, adopting this strategy may provide one good example of how to achieve "good health at low cost".

Interstitial class II-positive cell depletion by donor pretreatment with gamma irradiation. Evidence of differential immunogenicity between vascularized cardiac allografts and islets

We used an allograft pretreatment regimen involving lethal total-body gamma irradiation of donor rats eight days prior to transplantation to compare directly the immunogenicty of immediately-vascularized heart allografts with isolated, neovascularized pancreatic islet allografts. TBI pretreatment of heart donors (IHT) caused a modest prolongation in cardiac allograft survival compared with controls in a low-responding fully-allogeneic strain combination, Lewis-to-ACI. The addition of 10(5) donor-type dendritic cells (DCs) at the time of transplantation reversed the prolongation of IHT in this strain combination. Donor pretreatment with TBI did not lead to prolonged cardiac allograft survival in either a high-responding combination, ACI-to-Lewis, or in an MHC class II-compatible strain combination, F344-to-Lewis. In contrast, islets from irradiated donors (IIT) showed markedly prolonged survival in both low-responding (Lewis-to-ACI) and high-responding (W/F-to-Lewis) strain combinations. The addition of 10(5) donor-type DCs to the islets at the time of transplantation caused the rejection of only two of six IIT in the Lewis-to-ACI combination. Combined pretreatment regimens involving TBI-pretreated cardiac allografts--such as recipient immunosuppression with peritransplant cyclosporine (10 mg/kg on days 0, 1, and 2) or the combination of TBI (1000 cGy on day -3) and cyclophosphamide (300 mg/kg on day -5) in a pretreatment regimen--did not lead to synergistic graft prolongation in the low-responding Lewis-to-ACI combination. Immunohistologic studies showed that eight days after TBI rat hearts and islet were both greater than 90% depleted of class II (0X6+) interstitial dendritic cells while class I (0X18+) expression was unchanged. IIT are able to increase class II expression when donors are treated with recombinant gamma interferon (4000 U/day on days -3, -2, and -1). MLR data showed that ACI recipients of Lewis IIT reacted normally to donor (Lewis) and third-party (W/F) stimulator cells greater than 100 days after transplantation. The apparent greater immunogenicity of heart allografts as compared with islets in this model could be due to (1) a quantitative difference between the number of residual class II-positive cells in hearts and islets or a greater nnon-MHC antigenic load in the heart grafts given its larger size, or (2) a quanlitative difference between hearts and islets due to the presence of a vascular endothelium in the immediately vascularized heart that can present alloantigen and provide a major stimulus to rejection.