Modelling the daily risk of Ebola in the presence and absence of a potential vaccine

Ebola virus d one of the deadliest viral diseases,with a mortality rate around 90%d damages the immune system and organs,with symptoms including episodic fever,chills,malaise and myalgia.The Recombinant Vesicular Stomatitis Virus-based candidate vaccine(rVSV-ZEBOV)has demonstrated clinical efficacy against Ebola in ring-vaccination clinical trials.In order to evaluate the potential effect of this candidate vaccine,we developed risk equations for the daily risk of Ebola infection both currently and after vaccination.The risk equations account for the basic transmission probability of Ebola and the lowered risk due to various protection protocols:vaccination,hazmat suits,reduced contact with the infected living and dead bodies.Parameter space was sampled using Latin Hypercube Sampling,a statistical method for generating a near-random sample of parameter values.We found that at a high transmission rate of Ebola(i.e.,if the transmission rate is greater than 90%),a large fraction of the population must be vaccinated(>80%)to achieve a 50%decrease in the daily risk of infection.If a vaccine is introduced,it must have at least 50%efficacy,and almost everyone in the affected areas must receive it to effectively control outbreaks of Ebola.These results indicate that a low-efficacy Ebola vaccine runs the risk of having vaccinated people be overconfident in a weak vaccine and hence the possibility that the vaccine could make the situation worse,unless the population can be sufficiently educated about the necessity for high vaccine uptake.

A metapopulation model for the spread of MRSA in correctional facilities

The spread of methicillin-resistant strains of Staphylococcus aureus(MRSA)in health-care settings has become increasingly difficult to control and has since been able to spread in the general community.The prevalence of MRSA within the general public has caused outbreaks in groups of people in close quarters such as military barracks,gyms,daycare centres and correctional facilities.Correctional facilities are of particular importance for spreading MRSA,as inmates are often in close proximity and have limited access to hygienic products and clean clothing.Although these conditions are ideal for spreading MRSA,a recent study has suggested that recurrent epidemics are caused by the influx of colonized or infected individuals into the correctional facility.In this paper,we further investigate the effects of community dynamics on the spread of MRSA within the correctional facility and determine whether recidivism has a significant effect on disease dynamics.Using a simplified hotspot model ignoring disease dynamics within the correctional facility,as well as two metapopulation models,we demonstrate that outbreaks in correctional facilities can be driven by community dynamics even when spread between inmates is restricted.We also show that disease dynamics within the correctional facility and their effect on the outlying community may be ignored due to the smaller size of the incarcerated population.This will allow construction of simpler models that consider the effects of many MRSA hotspots interacting with the general community.It is suspected that the cumulative effects of hotspots for MRSA would have a stronger feedback effect in other community settings.