Methods and Metrics

Methods -thresholds for each indicator are described below. Source of COVID-19 case data is SC DHEC:

  • Six Indicators

*Cases Per Day Per 100k Population – This is the 7-Day average of the number of reported cases per day per 100k residents, as reported on the South Carolina DHEC site; it is the total number of confirmed cases combined with the total number of probable cases for Chester and Lancaster Counties. Available at: https://scdhec.gov/covid19/sc-testing-data-projections-covid-19

*Test Positivity  – This number is the 7-Day average of the percent of positive tests, determined using the Test/Test method. This number is reported by South Carolina DHEC with a two-day lag, available at: https://scdhec.gov/covid19/south-carolina-county-level-data-covid-19

*ICU Beds in Use Per Week– This is the number of hospital beds in use for the past week for Charleston area hospitals, as reported by The Department of Health and Human Services. This data is updated weekly and corresponds to the previous week's data (Friday through the following Thursday). Available at: https://healthdata.gov/dataset/covid-19-reported-patient-impact-and-hospital-capacity-facility

*Effective Reproduction Number (Rt)– This is the estimate of infectious disease transmissibility. The R-Naught indicates the average number of people who are infected by each person who gets infected. If R-Naught is greater than 1 the epidemic will continue to be sustained. If R-Naught drops below 1 eventually the epidemic will cease to exist. The time-dependent reproduction number (R) is inferred from disease incidence time series, and is calculated by inputting the number of new cases via an algorithm created by the authors: Thompson RN, Stockwin JE, van Gaalen RD, Polonsky JA, et al. Improved inference of time-varying reproduction numbers during infectious disease outbreaks. Epidemics (2019). Available at: https://shiny.dide.imperial.ac.uk/epiestim/

*Number of Reported Variants in South Carolina– This is the number of cases of both the South African (B.1.351) and United Kingdom (B.1.1.7) SARS-CoV-2 variant strains reported by DHEC, available at: https://scdhec.gov/covid19/mis-c-covid-19-variants

*Percentage of Population Vaccinated– This is the percentage of the aggregate number of people who have currently been vaccinated by county. This metric does not include individuals who may move across state lines in order to access vaccines. This data is reported by DHEC and is available at: https://scdhec.gov/covid19/covid-19-vaccination-dashboard



 

 

  • Growth in Number of Reported COVID-19 Infections: Weekly change of reported infections for the Lancaster region (Percentage change in 7-day average of new infections over the past week).

*This metric is updated daily M-F, while the remaining metrics are updated weekly.

GREEN – The percent change in the 7-day average in growth of confirmed cases over the past week is 1% or less (or negative).

YELLOW – The percent change in the 7-day average in growth of confirmed cases over the past week is 2-5%.

RED – The percent change in the 7-day average in growth of confirmed cases over the past week is 6% or greater.

 

  • Trajectory of documented cases (Increasing or Decreasing): Downward trajectory of documented cases within a 14-day period.  

GREEN -There is a negative slope of the trend line (downward trajectory) of the daily 7-day average of number of cases for each of the past two-weeks.

YELLOW -There is a negative slope of the trend line (downward trajectory) of the daily 7-day average of number of cases for one of the past two weeks (one week positive, one week negative).

RED – There is a positive slope of the trend line (upward trajectory) of the daily 7-day average of number of cases for each of the past two-weeks.

 

  • Number of Reported COVID-19 cases in last week: Number of reported cases per week is manageable with regard to medical care and capacity for effective contract tracing.

GREEN -Number of reported cases per week less than 1 per 1,000 population.

(Population = 130,256: equivalent to 13 or fewer cases a week)

YELLOW - Number of reported cases per week is 1-5 per 1,000 population.

(Population = 130,256: equivalent to 13 - 65 cases a week)

RED - Number of reported cases per week greater than 5 per 1,000 population.

(Population = 130,256: equivalent to GT 65 cases a week)

 

  • Diagnostic Testing Availability: Diagnostic testing availability for all people with COVID-19 symptoms.

GREEN – 100% of those meeting criteria and seeking testing receive testing

YELLOW – 80%-99% of those meeting criteria and seeking testing receive testing

RED – Less than 80% of those meeting criteria and seeking testing receive testing

 

  • Return of Diagnostic Test Results: Return of diagnostic test results is done in a timely manner and that allows for rapid contact tracing.

GREEN – Results returned within average of 2 days from sample collection

YELLOW – Results returned within average of 3-4 days from sample collection

RED – Results returned within average of 5 or more days from sample collection

 

  • Hospital Capacity to treat Critical Patients: Area hospitals have ability to treat critical patients requiring hospitalization without resorting to crisis standards.

GREEN – Area hospitals have greater than 15% of total staffed ICU beds available

YELLOW – Area hospitals have between 5% - 15% of total staffed ICU beds available

RED – Area hospitals have less than 5% of total staffed ICU beds available

 

  • Super spreader events and congregant facility outbreaks: Number of super spreader events or cluster outbreaks of significant magnitude (GT 10 cases in discrete social group or setting) in past 30 days.

GREEN – None reported in past 30 days

YELLOW – 1-2 reported in past 30 days

RED – 3+ reported in past 30 days

 

*Metrics shown reflect the day events occurred, not the day they were reported. There is typically a one-day lag in the release of data from DHEC on newly diagnosed cases. There is typically a two-day lag in the release of data from DHEC on percent positive of COVID-19 Tests.