Participation by acute care hospitals in the local healthcare coalition (HCC). The indicator is calculated as the number of acute care hospitals in the coalition area that participate in the local healthcare coalition (HCC), divided by the total number of acute care hospitals within that HCC region, then multiplied by 10. The same participation rate applies to all counties that are within that HCC.

Acute care hospitals are central to outbreak response with roles including case identification and implementing infection prevention and control practices to protect healthcare workers and patients.¹ Acute care hospitals are one of the core member types within healthcare coalitions, so their participation in these coalitions provides a foundation for outbreak preparedness work. Healthcare coalitions are the primary entities leading the emergency planning and coordination activities across a geographic region, allowing for better communication and resource sharing, which are essential in coordinating outbreak response.

Accreditation among acute care or critical access hospitals through any one of the following programs: the Health Facilities Accreditation Program (HFAP), the National Accreditation for Healthcare Organizations (DNV), or the Joint Commission (JC). All 3 of these programs are approved accreditation programs from the Centers for Medicare and Medicaid Services (CMS) that have emergency preparedness standards.

Hospital surge capacity within the healthcare coalition (HCC) region. This indicator is calculated by first calculating the Hospital Medical Surge Preparedness Index (HMSPI) among hospitals in the dataset, averaging scores from both years.² The HMSPI includes four subdomains based on the “Science of Surge” construct: staff, supplies, space, and system. The surge index is normalized across hospitals within the state. Next, the HMSPI scores were averaged across hospitals within each healthcare coalition (HCC). All counties within the HCC receive the same score.

Outbreaks can create surging demand for critical care resources, particularly hospital resources, such as intensive care beds, personal protective equipment (PPE), and healthcare personnel. Measuring hospital-based medical surge capacity is of critical importance in assessing healthcare preparedness for outbreaks.³

Staffing capacity for critical care nurses and physicians. To calculate this indicator, the first step is to calculate the number of critical care nurses per 100,000 population and number of intensivist physicians (i.e. trained in critical care medicine) per 100,000 population in the county. Next, these two measures are averaged and min-max scaled from 0-10 based on data from counties across the state.

The nursing taxonomy codes included are:
163WC0200X - Registered Nurse (Critical Care Medicine) 364SC0200X - Clinical Nurse Specialist (Critical Care Medicine) 363LC0200X - Nurse Practitioner (Critical Care Medicine) 367500000X - Nurse Anesthetist, Certified Registered

The physician taxonomy codes included are:
207LC0200X - Physician/Anesthesiologist (Critical Care Medicine) 207RC0200X - Internal Medicine (Critical Care Medicine) 207VC0200X - Obstetrician & Gynecologist (Critical Care Medicine) 2084A2900X - Psychiatry & Neurology (Neurocritical Care) 2086S0102X - Surgery (Surgical Critical Care)

The presence of critical care nurses and physicians in the region is an indicator of potential resource availability in the immediate geographic area to provide local capacity for handling routine healthcare needs. Areas that have lower baseline capacity may be more prone to strain during outbreak incidents.

Extent of COVID-19 vaccination among nursing home staff. This indicator is calculated as the proportion of nursing home staff in the county who were up-to-date with their COVID-19 vaccinations. The vaccination rates were weighted based on the number of certified beds at the facility and averaged across facilities in the county. This weighted average was multiplied by 10 to create the indicator on a 0-10 scale.

Nursing home staff represent an important category of healthcare workers that serve a population of older adults, who are at higher risk of morbidity and mortality from a wide variety of communicable diseases. Vaccination is an important measure to prevent transmission of diseases between staff and residents, as well as a measure to help preserve available workforce during outbreaks. A high vaccination rate for COVID-19 among nursing home staff is indicative of the ability and willingness of these institutions and communities to be vaccinated for a novel pathogen, which could be applied to other vaccine-preventable diseases.

Primary care capacity in the county. To calculate this indicator, the first step is to calculate the percent of the county population that the does not have a geographic designation from the Health Resources and Services Administration (HRSA) as a Health Professional Shortage Area (HPSA) for Primary Care providers shortages. This percent is multiplied by 10 to create the indicator on a 0-10 scale.

Primary care is an important component of general healthcare and is included in this subdomain, which assesses baseline healthcare capacity. Lower levels of baseline healthcare capacity are associated with poorer general population health, in part due to delayed or deferred necessary care, which may lead to more complex healthcare needs during outbreaks.

Staffing capacity for emergency medical technicians (EMTs) and paramedics. This indicator is calculated as the number of EMTs and paramedics in the county, divided by the county population, then min-max scaled based on data from counties across the state, and scaled to a 0-10 scale.

Influenza vaccination among healthcare workers at acute care hospitals. This indicator is calculated as the percent of healthcare workers at acute care hospitals in each county who are vaccinated for influenza in each of the 3 seasons included. The average vaccination rate for each county is calculated by averaging the percent vaccinated across the 3 influenza seasons. This percent is multiplied by 10 to create the indicator on a 0-10 scale.

The Healthy People 2020 goal is to have 90% of healthcare workers vaccinated for influenza by the 2020-2021 season. Vaccination is an important measure to prevent transmission of diseases between staff and patients, as well as a measure to help preserve available healthcare workforce during outbreaks. A high healthcare worker vaccination rate for influenza is indicative of the presence of a robust immunization program, which could be applied to many vaccine-preventable diseases.⁴

The preventable hospitalizations indicator is a measure of healthcare quality, and is calculated from the County Health Rankings Preventable Hospital Stays measure, which reports the age-standardized rate of hospitalizations for ambulatory-care sensitive conditions per 100,000 Medicare enrollees. To calculate the indicator, we applied min-max scaling from 0-10 to the CHR Preventable Hospital Stays measure based on data from counties within the state, and reversed the polarity such that a higher score on this indicator means there were fewer preventable hospitalizations.

Reducing preventable hospital stays in the county helps reduce the strain on healthcare resources during outbreak situations.

This indicator of nursing home quality is based on the percent of nursing home residents at facilities within the county that did not have an infection control citation in the past 3 years, among facilities that had an inspection. This percent was multiplied by 10 to create the indicator on a 0-10 scale.

Nursing homes are congregate living facilities for older adults, who are a vulnerable population for a wide variety of communicable diseases. Infection control practices at these facilities help to minimize disease transmission in these settings.⁵

Adequacy of nursing home staffing. The indicator is calculated as the percent of Nursing Homes in the county that meet CMS recommended staffing ratios for RN, LPN and CNA, multiplied by 10 to create an indicator on a 0-10 scale. The recommended staffing ratios are: >=0.75 RN hours per resident per day, >=0.55 LPN/LVN hours per resident per day, and >=2.8 CNA hours per resident per day.

Nursing homes are congregate living facilities for older adults, who are a vulnerable population for a wide variety of communicable diseases.

Studies have linked adequate staffing ratios to improved nursing home quality.⁶

The Hospital Quality indicator is calculated as the average CMS Overall Star Rating across acute care and critical access hospitals, among counties with at least 50% complete data. Since the CMS Overall Star Rating is provided on a 5-point scale, the average rating is multiplied by 2 to create this indicator on a 10-point scale.

The Overall Star Rating is a summary of several quality measures, including mortality, safety of care, readmission, patient experience, and timely and effective care.⁷ Better hospital quality is important in helping to ensure better patient outcomes.

Social Capital is a measure of the degree of social engagement among people within a community. The PSU-SC Index (2014) is a composite score of civic engagement comprised of the number of membership organizations (i.e., religious organizations, civic and social associations, business associations, political organizations, professional organizations, labor organization, bowling center, fitness and recreational sports centers, golf courses and country clubs, and sports teams and clubs) per 1,000 population, voting rate in presidential elections, the response rate to the Census Bureau's decennial census, and the number of non-profit organizations per 10,000 population. The indicator was min-max scaled from 0-10.

Social capital is associated with stronger community networks, which can facilitate preparedness awareness and planning, ease communications, and are instrumental in supporting responses to emergency, outbreak, and disaster events.⁸

Use of the Surescripts Network by physicians using an electronic health record to create electronic prescriptions. This indicator measures the proportion of physicians in a county e-prescribing using Surescripts, multiplied by 10 to create indicator scores ranging from 0-10.

Use of electronic prescription systems helps to streamline prescribing, which reduces medical errors and costs. Use of these systems also helps make prescription data more accessible to public health authorities for surveillance and assessment purposes.⁹

Number of CERT programs in a county per capita. The indicator was standardized using the min-max technique to scale scores from 0-10 based on data from counties across the state.

CERT programs can provide staffing in emergency situations associated with surges in demand for disaster response services, such as during disease outbreaks.

Registered environmental health specialists per capita. The indicator was standardized using the min-max technique to scale scores from 0-10 based on data from counties across the state.

Environmental health professionals perform important tasks in outbreak and emergency situations which require use of shelters or other mass care sites (e.g., water supply testing, food safety inspections, shelter assessment, sanitation evaluations, safety determinations).

Population coverage for wastewater surveillance testing. This indicator was calculated as the proportion of the county population that resides within a sewer shed participating in wastewater surveillance testing, multiplied by 10 to create indicator scores ranging from 0-10.

Wastewater surveillance can be an important piece of a county's monitoring of population-level disease trends. Counties served by sewer sheds with the infrastructure to participate in wastewater surveillance may be better prepared to identify and track disease outbreaks.

Pharmacist workforce in the county, per capita. The indicator was standardized using the min-max technique to scale scores from 0-10 based on data from counties across the state.

The pharmacy taxonomy codes included are:

• Pharmacist: 183500000X
• Ambulatory Care: 1835P2201X
• Critical Care: 1835C0205X
• Geriatric: 1835G0303X
• Nuclear: 1835N0905X
• Nutrition Support: 1835N1003X
• Oncology: 1835X0200X
• Pediatrics: 1835P0200X
• Pharmacist Clinician/Clinical Pharmacy Specialist: 1835P0018X
• Pharmacotherapy: 1835P1200X
• Psychiatric: 1835P1300X
• Pharmacy technician: 183700000X

Pharmacists dispense medications (including vaccines) and, as such, are a crucial workforce component for distributing medical countermeasures in response to a disease outbreak.

COVID-19 population-wide vaccination rates. This indicator is calculated as the proportion of the county's population who have completed the primary series of the COVID-19 vaccine, multiplied by 10 to create indicator scores ranging from 0-10.

This indicator reflects the capacity of a county to execute a mass vaccination campaign, as well as the ability and willingness of the county's population to comply with public health guidelines regarding a new vaccine.

Completeness of vaccination requirements among school-age children. This indicator is calculated as the proportion of the county's children who have received all required immunizations for school enrollment, averaged over 3 school years (2019-2020, 2020-2021, and 2021-2022), and multiplied by 10 to create indicator scores ranging from 0-10.

Compliance with school enrollment guidelines regarding pediatric vaccination reflects the county's capacity to administer pediatric immunizations, as well as parental willingness to comply with these guidelines. Such acceptance of public health guidance is crucial during outbreaks where existing immunity can help slow down disease transmission, or outbreaks that may require the rapid immunization of pediatric populations.

Population distance to influenza vaccination providers. This indicator is calculated as the proportion of the population residing within specific distance buffers of an influenza vaccination provider, with the distances varying by urbanicity. The distances were based on the CMS travel distance standards for healthcare plan network adequacy for primary care services, based on county type: 5 miles for large metropolitan counties; 10 miles for metropolitan counties; 20 miles for micropolitan counties; 30 miles for rural counties; and 60 miles for counties with extreme access considerations.¹⁰

Access to vaccination sites is an important consideration in a county's response to a disease outbreak.

Influenza vaccination rate in the county. This indicator is calculated as the proportion of persons vaccinated against influenza in the county, multiplied by 10 to create indicator scores ranging 0-10.

Influenza vaccination uptake assesses a county's infrastructure to administer immunizations, as well as its populations' overall receptivity to obtaining recommended vaccines.

Housing Affordability is a measure of access to affordable housing. This indicator is calculated as the percent of households that spend less than 50% of their household income on housing, scaled on a 0-10 scale.

Housing is a basic need that affects many aspects of health and healthcare. Safety net programs exist to help individuals and families pay for housing, such as Section 8 and other housing support programs. Improving access to such programs and/or increasing availability of lower-cost housing options would help alleviate problems with housing affordability.

Housing Quality is a measure of the quality of available housing in the county. This indicator is calculated as the percent of households that do not have any of the following four housing problems - overcrowding, high housing costs, lack of kitchen facilities, or lack of plumbing facilities. The indicator is scaled on a 0-10 scale.

Housing is a basic need that affects many aspects of health and healthcare. Poor housing quality may increase the risk of communicable disease transmission within a household (e.g., due to overcrowding or lack of plumbing) or impede the recovery from such diseases.¹¹

The Food Environment Index measures access to healthy foods by considering the distance an individual lives from a grocery store or supermarket, locations for healthy food purchases in communities, and cost barriers in accessing healthy foods. Specifically, it is expressed as a scale from 0 (worst) to 10 (best) that equally weights the following two indicators of the food environment: 1) The percentage of the population that is low income (≤200 percent of the federal poverty threshold) and that does not live close to a grocery store; and 2) the percentage of the population that did not have access to a reliable source of food during the past year.¹²

Lower access to healthy foods is associated with greater reliance on sources of unhealthy foods.¹³ Better access to grocery stores is associated with better health outcomes including lower mortality rates.¹⁴ Better access to healthy foods is an important social determinant of health that contributes to outbreak-related health outcomes.

The SNAP Access indicator measures how well this food assistance program is reaching people who may benefit from this food assistance program. SNAP is a federal program that provides financial assistance to low-income families to purchase food, and CalFresh is California's implementation of this federal program. The indicator is represented by the CalFresh Program Reach Index, which aims to estimate the percent of the population enrolled in CalFresh among those who are eligible.¹⁵ The Program Reach Index is expressed as a proportion, which was multiplied by 10 to scale this indicator from 0-10.

This program aims to reduce food insecurity among low-income families by reducing some cost barriers to purchasing healthy foods. Food insecurity may lead to a poor diet, which increases vulnerability to infection and adverse health outcomes.¹⁶

The WIC Access indicator measures how well this food assistance program is reaching people who may benefit from this food assistance program. WIC is a federal program that provides food assistance to low-income pregnant women, recent mothers, infants and children under age 5. This indicator is calculated as the proportion of the population that are enrolled in WIC among those who are eligible, scaled from 0-10. This is a state-level indicator.

This program aims to reduce food insecurity during a critical life stage for healthy eating among low-income families by reducing some cost barriers to purchasing healthy foods. Food insecurity may lead to a poor diet, which increases vulnerability to infection and adverse health outcomes.¹⁷

The Health Insurance - Adults indicator is a measure of the prevalence of health insurance among people ages 18-64 years old. The indicator is calculated as the number of people within this age group that have any type of health insurance divided by the total population in this age group; this proportion is multiplied by 10 to create an indicator with a maximum range of 0-10.

Health insurance represents an important factor in accessing healthcare, both on a routine basis as well as during outbreak conditions. Having health insurance is associated with better continuity of care, preventive care, and health outcomes including mortality from communicable diseases.^{18, 19, 20, 21} Because adults over 65 years old in the US are eligible for Medicare health insurance, this indicator focuses on adults ages 18-64, who are more reliant on employer-based health insurance.

The Health Insurance - Minors indicator is a measure of the prevalence of health insurance among people <19 years old. The indicator is calculated as the number of people within this age group that have any type of health insurance divided by the total population in this age group; this proportion is multiplied by 10 to create an indicator with a maximum range of 0-10.

Medicaid and the State Children's Health Insurance Program (SCHIP) are public programs that provide critical sources of coverage for low-income non- elderly populations, and better access and expanded eligibility to programs such as these can increase health insurance rates.²² Lack of health insurance can cause delayed or deferred care, which may lead to higher risk of infections and poorer clinical outcomes in children.^{23, 24}

The Quality of Unemployment Benefits indicator is a measure of the extent to which the unemployment benefits may help keep a family out of poverty. This indicator is calculated as the ratio of the state maximum total weekly unemployment benefits, divided by the county's average Supplemental Poverty Measure (SPM) poverty threshold (based on weekly income) for a family with 2 parents and 2 kids. The SPM accounts for differences in local cost of living, such that the poverty threshold in a high cost of living area is higher than the threshold in a low cost of living area.

Unemployment insurance is an important social safety net program that helps buffer financial instability, which may occur as a result of illness. Loss of employment can result in loss of health insurance and income to pay for housing, food, and other household necessities required for daily living.²⁵

Broadband Access is an important factor affecting access to a range of services, including safety net services. Studies have shown that broadband connection is a predictor of better access to unemployment benefits.²⁶ Broadband access is also associated with lower unemployment rates, especially in rural areas.²⁷ This indicator is calculated as the percentage of households with any type of broadband internet connection (cable, DSL, fiber-optic, cell phone, or satellite).

Improved access to social safety net services, including unemployment benefits, helps to mitigate the health impacts of unemployment.

Community Factors are population and environmental characteristics that result in some areas having higher risks of adverse health outcomes. This indicator (which constitutes the entire domain) is calculated as the proportion of the county's population that has an Environmental Justice Index score in the lower 75th percentile in the US. EJI assesses the Environmental Burden, Health Vulnerability, and Social Vulnerability of communities, multiplied by 10 to scale the indicator from 0-10. A higher score indicates lower levels of vulnerability in the county.

Community factors or social determinants of health are strongly associated with increased communicable disease risk and morbidity from such health problems.^{28, 29} Therefore, this domain contributes to the overall COPI score by accounting for some social determinants that may require additional consideration when preparing for future outbreaks.