Table A2

Variable notation and descriptions

VariablesNotationShort description of variables
SIR and SIV Loops
Susceptible PopulationSThe number of people susceptible to infection
Infectious PopulationIThe number of susceptible people get infected
Recovered PopulationRThe number of people recovered from infection
Contact RateCRThe number of Infectious people contact with susceptible people
Average Duration of InfectivityDThe average length of time people are infectious
Infection RateIRTotal number of contacts
InfectivityIFThe likelihood of a person contracting an infection
Recovery RateRRTotal number of people recover from an infection
Vaccinated PopulationVThe number of vaccinated people
Vaccination RateVRTotal number of vaccinated people
Average Duration of InoculationDIThe average length of time people are inoculated
VSC Order Fulfillment Loop
Vaccine DemandVDPopulation eligible for receiving vaccines
Vaccine Order RateVORThe total number of vaccine orders for vaccination
Vaccine Order BacklogVOBUnsatisfied/ unfulfilled vaccine orders
Desired Supply Rate for VaccineDSRVVaccination site's target supply rate
Target Delivery DelayTDDA certain amount of time required to fill the vaccine orders
Vaccine InventoryVIVaccine inventory on hand
Vaccine Supply RateVSRThe total number of vaccine orders supplied
Vaccine Order Fulfillment RatioVOFRA function of maximum vaccine supply rate and desired vaccine supply rate
Vaccine Delivery DelayVDDThe average delay between the placement and the receipt of the vaccination order
Inventory Control Loop
Maximum Vaccine Supply RateMVSRThe maximum number of supplies given the VI in stock and VMOPT
Vaccine Minimum Order Processing TimeVMOPTThe amount of time it takes between the vaccine order being placed and shipped
Vaccine Inventory Coverage RatioVICRThe number of days the vaccination site could supply (service level of the vaccination site)
Desired Vaccine InventoryDVIThe volume of inventory required to keep a vaccination site's desired service level of full and dependable delivery
Expected Vaccination DemandEVDExpected/forecasted demand
Vaccine Safety StockVSSAdditional vaccine inventory in stock to prevent stockouts
Change in Vaccination DemandCVDThe discrepancy between EVD and the vaccination site’s VOR over a period determined by the TAOR
Time to Average Order RateTAORThe time between vaccine orders
Vaccine Inventory GapVIGThe disparity between DVI and VI
Vaccine Inventory Adjustment TimeVIATThe time required to take the inventory to the desired level
Order Placement Loop
Desired Vaccine OrderDVOThe vaccination site's desired vaccine order
Vaccination Site's Order RateVSORThe total number of vaccine orders placed
Vaccine Transhipment RateVTRThe number of vaccines shipped to vaccination site via transshipment
Vaccine Transhipment Delivery RateVTDRThe total number of vaccines delivered to vaccination site via transshipment
Production Loop
Desired ProductionDPDesired number of vaccines to be produced
Expected Vaccination Site's DemandEVSDExpected/forecasted vaccination site's demand
Production Release RatePRRThe total number of vaccines released for manufacturing
Work In Process InventoryWIPIThe number of vaccines accumulated by difference between PRR and PC
Product CompletionPCThe total number of vaccines produced
Work in Process GapWIPGThe pending production line (the difference between DWIP and WIPAT)
Desired Work In ProcessDWIPDesired number of vaccines to be accumulated in the production line
Work In Process Adjustment TimeWIPATThe time it takes to modify WIPG in line with the desired level
Manufacturing Lead TimeMLTThe average cycle time for the vaccine production
Manufacturer's InventoryMIManufacturer's vaccine inventory on hand
Manufacturer's Inventory GapMIGThe disparity between DMI and MI
Maximum Manufacturer Shipment RateMMSRThe maximum number of shipments given the MI in stock and MMOPT
Manufacturer Shipment RateMSRThe total number of vaccines shipped from Manufacturer
Manufacturer Minimum Order Processing TimeMMOPTThe amount of time it takes between the vaccine order being placed and shipped at the manufacturer
Closing the Loop
Vaccine Usage DurationVUDVaccine usage until expiration or expired vaccines which depends on the vaccine’s shelf life
Used VaccineUVUsed or expired vaccines
Uncontrollable Vaccine DisposalUVDThe flow of used vaccines to disposal due to the limited collection capacity
Uncontrollably Disposed VaccinesUDVA variable that accumulates the uncontrollably disposed vaccines
Collection
Vaccine Collection RateVCRThe flow of used vaccines to the collection and inspection facilities
Collected VaccinesCVThe inventory of collected reused vaccines
Collection CapacityCCThe maximum volume of vaccines handled by the collection and inspection facilities per week
Vaccines Accepted for ReuseVARThe flow of used products that have passed inspection and are appropriate to be remanufactured
Vaccines Rejected for ReuseVRFRThe flow of used products that have not passed inspection and are appropriate to be remanufactured
Inspection TimeITThe time inspect calculated based on several reuses (remaining non-expired doses) and remaining shelf life
Failure PercentageFRA percentage of failing in inspection
Remanufacturing
Remanufacturing CapacityRCThe maximum volume of reused products that can be remanufactured per week
Vaccine Remanufacturing RateVRRThe flow of remanufactured vaccines
Reusable VaccinesRVThe inventory of used products that passed inspection and are ready to be remanufactured
Controllable Vaccine DisposalCVDThe flow of surplus stock of used vaccines to prevent costly accumulation if there is not enough remanufacturing capacity to handle them
Uncontrollable DisposalUCDThe flow of used vaccines to disposal due to the limited collection capacity
Reusable Stock Keeping TimeRSTUnused vaccines for some time
Reuse RatioRRThe ratio of ERR to the number of EUV
Expected Remanufacturing RateERRThe forecast of remanufacturing rate
Expected Used VaccinesEUVThe forecast of used products
Vehicle Capacity
Desired Number of VehiclesDNVThe desired number of vehicles to transport vaccines
Average Capacity of VehiclesACVThe average amount of vaccines can be transported by vehicles
Vehicle CapacityVCThe maximum vaccine transshipment rate that is restricted by ACV
Number of Available VehiclesNAVThe discrepancy between VC and VUT
Vehicle Used for TransportationVUTThe number of vehicles used for transshipment
Vehicle Adjustment TimeVATThe time required to prepare the vehicles
Transshipment
Vaccine Transshipment RateVTRThe total number of vaccines shipped from vaccine site n to vaccine site k
Aggregate Inventory LevelAILThe total number of the available inventory across all vaccination sites
Allocate InventoryAIAllocation decision of inventory from available inventory stock at vaccination site n to vaccination site k based on vaccination site k's DVO, MDBV, and AFR
Allocation Fill RateAFRIf the vaccination site n has available inventory to allocate, the AFR score becomes one, else it is zero
Minimum Distance Between Vaccination SitesMDBVEnsures the minimum distanced vaccination site k is matched to vaccination site n to allocate vaccines
Transshipment Lead TimeTLTThe time that elapses between vaccine transshipment allocation and the delivery at vaccination site k

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