The VPI tool was created by East Carolina University, using funds from the 2020 COVID-19 Recovery Act, as a guide to help North Carolina decision-makers identify priority groups (Phases 1A and 1B) when planning for the equitable allocation and distribution of the COVID-19 vaccine.
The VPI tool displays NC counties and Census tracts by risk priority for the COVID-19 vaccine, reflecting NC’s vaccination plan, which was developed based on the National Academy of Medicine (NAM) Framework for the Equitable Allocation of the COVID-19 Vaccine. The Vaccine Priority Index translates the NAM recommended Phase 1A and Phase 1B priority groups into a ranked index value. The methodology for the VPI can be found below.
How to use the NC VPI tool
To use the VPI tool, you must read and click “OK” to agree to the VPI terms of use. Select the VPI category from the Global Filter. High index values indicate higher priority areas; low index values indicate lower priority. The pop-ups over the geographic areas show the estimated count of high-priority individuals in each county and Census tract. Turn the map layers on or off on the right-hand panel to display the VPI, or the CDC’s Social Vulnerability Index (SVI). Zoom in to display key point locations, such as nursing homes, pharmacies, or health clinics. Use the filters on the left to filter for areas based on index categories or the number of priority individuals.
View counties
- On the Map Layers panel, click the eye icon to turn a layer on or off. Start by turning the Vaccine Priority Index – Counties layer on and turning off the Vaccine Priority Index – Census Tracts layer (so you can see the Counties layer). On the map, counties are shaded based on their VPI value. Darker colors indicate a higher priority; lighter colors indicate a lower priority.
- Click on a county and a pop-up opens that displays the numeric index value and the number of Phase 1A and Phase 1B individuals that live in that county. Priority individuals for Phases 1A and 1B include healthcare workers, first responders, residents in nursing homes and assisted living facilities, and individuals with chronic health conditions. The tool allows policymakers to easily identify how many people in each county and Census tract are eligible for vaccination in Phases 1A and 1B, and to visualize those areas with the highest priority.
- Scroll down in the pop-up to see additional measures, such as per capita income and poverty rate.
- Click the eye icon again to turn off the Vaccine Priority Index – County layer, and then turn on the Vaccine Priority Index – Census Tract layer.
- For additional information about how the VPI combines variables like poverty, race, age, and occupation to create the index, scroll down to the VPI Methodology section below.
View Census tracts within counties
- On the Map Layers panel, click the eye icon to turn a layer on or off. Start by turning the Vaccine Priority Index – Counties layer on and turning off the Vaccine Priority Index – Census Tracts layer (so you can see the Counties layer). On the map, counties are shaded based on their VPI value. Darker colors indicate a higher priority; lighter colors indicate a lower priority.
- Click on a county and a pop-up opens that displays the numeric index value and the number of Phase 1A and Phase 1B individuals that live in that county. Priority individuals for Phases 1A and 1B include healthcare workers, first responders, residents in nursing homes and assisted living facilities, and individuals with chronic health conditions. The tool allows policymakers to easily identify how many people in each county and Census tract are eligible for vaccination in Phases 1A and 1B, and to visualize those areas with the highest priority.
- Scroll down in the pop-up to see additional measures, such as per capita income and poverty rate.
- Click the eye icon again to turn off the Vaccine Priority Index – County layer, and then turn on the Vaccine Priority Index – Census Tract layer.
- For additional information about how the VPI combines variables like poverty, race, age, and occupation to create the index, scroll down to the VPI Methodology section below.
Use the filters to investigate special populations and priority areas
Using filters in combination with layers allows the user to tailor questions and investigate more detailed connections between variables.
- Keep the VPI – Census Tract layer on, and zoom back out to the state level.
- Using the filter panel on the left-hand side of the map, go to the Vaccine Priority Index Category filter and pick the “High” category. The map filters to show only those Census tracts in the highest priority group.
- Keeping the Vaccine Priority Index – Category filter on, scroll down until you see the filter for Total Population Age 65 and Over. The range note on the filter tells you that, for North Carolina Census tracts, this variable ranges from a low of 0 to a high of 3,933 . We want to identify those high-priority tracts that also have an especially high number of individuals over 65.
- Enter a range value of 2,000 to 3,933 in the filter. This filters your results to only display high priority tracts that also have 2,000 or more people over age 65. Only one Census tract shows up, in Rutherford County (west of Charlotte).
- Keeping the over 65 filter as is, go back up to the Vaccine Priority Index – Category filter, and change the category to “Low.” Two Census tracts show up: one in Chatham County and one in Transylvania County. Even though these tracts have low VPI values, they nonetheless have a high number of residents over age 65. These tracts might have a high per capita income or some other factor that reduces their overall risk, but it still might be important to know that they are among the highest in the state in terms of number of individuals over age 65.
VPI Methodology
The VPI contains 14 variables that describe risk, vulnerability, and vaccine priority relative to the COVID-19 virus. Eleven of the variables are derived from Census data. Two variables are from the CDC’s Diabetes Surveillance System, and one is from the Center for Medicare and Medicaid Services’ Chronic Conditions Data Warehouse. The 14 variables are combined into 5 themes: social and economic status; minority status and language; housing situation; at-risk population; and health status. Index scores are calculated for each theme, then combined to create an overall VPI score for each county and Census tract.
The VPI is modeled on the CDC’s Social Vulnerability Index (SVI). The value of the VPI is that it “borrows” several core data variables from the SVI, and makes adjustments that incorporate risk and vulnerability factors that are pertinent to a pandemic scenario but are not included in the SVI. The VPI uses a similar ranking methodology to assign index values to geographical areas. Index values are calculated by ranking all of NC’s 100 counties and/or 2,195 Census tracts from low to high based on the individual variable. The ranked number is then used to create an index value. Individual index values are then combined to create “themes” and the themes are combined to create an overall VPI score. Census tracts or counties with low index values have low vulnerability (and priority), and those with high values have high vulnerability (and priority). The index value allows NC decision-makers to easily identify how many people in each county and Census tract are eligible for vaccination in Phases 1A and 1B, and to visualize those areas with the highest priority. At this time, only Phases 1A and 1B of the NAM framework are included. We have also included facilities that have high at-risk population groups, including prisons, meat processing plants, and long-term care facilities.
The variables and themes in the VPI are listed below.
VPI Theme 1: Social and Economic Status
- Percent below poverty
- Percent unemployed
- Average per capita income
- Percent with no high school diploma
VPI Theme 2: Minority Status and Language
- Percent minority
- Percent that speak English “less than well”
VPI Theme 3: At-Risk Population
- Percent age 65 or older
- Percent of the population who list an occupation in the high-risk group
VPI Theme 4: Housing
- Percent of households that are crowded (defined as more than 1 person per room)
- Percent of people who live in group quarters (defined as nursing homes, assisted living, prisons, dorms)
- Percent of housing that is multi-unit
VPI Theme 5: Health Status
- Percent of adults who have diabetes
- Percent of adults who are obese
- Percent of Medicare beneficiaries age 65 or older who have 2 or more chronic conditions