Appendices

Updated May 29, 2020
Appendix A – Glossary of Key Terms

Term

Definition

Term

Case Investigation & Contact Tracing

Definition

Fundamental activities that involve working with a patient who has been diagnosed with an infectious disease to identify and provide support to people (contacts) who may have been infected through exposure to the patient. This process prevents further transmission of disease by separating people who have (or may have) an infectious disease from people who do not.

Term

Close Contact

Definition

Someone who was within 6 feet of an infected person for at least 15 minutes starting from 2 days before illness onset (or, for asymptomatic patients, 2 days prior to specimen collection) until the time the patient is isolated.

Data are limited to precisely define the “prolonged exposure” to determine “close contact”, however 15 minutes of close exposure can be used as an operational definition for contact investigation. Factors to consider when defining close contact include proximity, the duration of exposure (e.g., longer exposure time likely increases exposure risk), whether the individual has symptoms (e.g., coughing likely increases exposure risk) and whether either the case patient or contact were wearing an N95 respirator (which can efficiently block respiratory secretions from contaminating others and the environment). At this time, differential determination of close contact for those using fabric face coverings is not recommended.

In healthcare settings, it is reasonable to define a prolonged exposure as any exposure greater than 15 minutes because the contact is someone who is ill. Brief interactions are less likely to result in transmission; however, symptoms and the type of interaction (e.g., did the person cough directly into the face of the individual) remain important.

More on Community-Related Exposures.

Term

Confirmed COVID-19 Case

Definition

Report of person with COVID-19 and meeting confirmatory laboratory evidence.

Term

Contact Elicitation Window

Definition

The timeframe when the case was likely infectious and not under isolation. This is the time period for which possible contacts should be elicited.

Term

Exposure

Definition

Having come into contact with a cause of, or possessing a characteristic that is a determinant of, a particular health problem. Principles of Epidemiology in Public Health Practice.

Term

First-responder

Definition

Law enforcement, fire services, emergency medical services, and emergency management officials. EMS Guidance.

Term

Healthcare personnel

Definition

All paid and unpaid people serving in healthcare settings who have the potential for direct or indirect exposure to patients or infectious materials, including body substances; contaminated medical supplies, devices, and equipment; contaminated environmental surfaces; or contaminated air. Potential Exposure at Work.

Term

Incubation period

Definition

Period of time between exposure to an infection and onset of symptoms

Term

Isolation

Definition

The separation of a person or group of people known or reasonably believed to be infected with a communicable disease and potentially infectious from those who are not infected to prevent spread of the communicable disease. Isolation for public health purposes may be voluntary or compelled by federal, state, or local public health order.

Term

Multigenerational Household

Definition

Households that consist of more than two generations living under the same roofexternal icon. Many researchers also include households with a grandparent and at least one other generation.

Term

Probable COVID-19 Case

Definition

Report of person meeting clinical AND epidemiologic evidence of COVID-19 but without confirmatory laboratory evidence. More about Probable COVID-19 Casepdf iconexternal icon.

Term

Quarantine

Definition

The separation of a person or group of people reasonably believed to have been exposed to a communicable disease but not yet symptomatic from others who have not been so exposed to prevent the possible spread of the communicable disease. Quarantine may be voluntary or compelled by federal, state, or local public health order.

Appendix B - Tips for Locating COVID-19 Cases and Contacts

When the locating information provided for a patient or close contact is insufficient, case investigation and contact tracing may come to an abrupt halt. The following list includes additional resources that may be used to obtain missing locating information and keep the investigation moving forward.

  • State DMV records
  • Online people search engines (may incur additional costs)
  • Health department records
  • Social media/mobile apps
  • Following up with the index case to ask for additional locating information on a contact
  • Jail and other correctional facility records
  • Property tax records
  • Frequent shopper cards
  • Women Infants and Children Program, Food Stamps and other social services records
  • Online white pages
  • Google maps
  • Employment records
Appendix C - Data Elements for Case Investigation and Contact Tracing Forms
Data Element Type Codes Notes
Case Investigation
Locating Information
Investigator Open Text Name of investigator
Investigator ID Numeric
Date Assigned for Investigation Date
Index patient ID Numeric Autogenerated
Lot Number (to link related cases and contacts) Numeric To track clusters
Patient Last Name Open Text
Patient First Name Open Text
Patient Preferred Name Open Text
DOB Date
Gender Categorical M/F/Other/Unk
Primary Language Open Text/Categorical
Interpreter used Categorical Y/N/U/R
Residential Street Address Open Text
City of Residence Open Text
County of Residence Open Text
State of Residence Open Text
Zip code Numeric
Tribal Affiliation Open Text
Born in the United States Categorical Y/N/U/R
Phone Number 1 Numeric
Phone Number 2 Numeric
Email 1 Open Text
Email 2 Open Text
Ok to Text Categorical Yes, No, Partial, Refused
Ok to Email Categorical Yes, No, Partial, Refused
Race Categorical Check all apply Use Censuspdf iconexternal icon or HHSexternal icon categories
Ethnicity Categorical Check box Use Censuspdf iconexternal icon or HHSexternal icon categories
Date of interview Attempt 1 Date
Interview 1 occurred Categorical Yes, No, Partial, Refused
Date of interview Attempt 2 Date
Interview 2 occurred Categorical Yes, No, Partial, Refused
Date of interview Attempt 3 Date
Interview 3 occurred Categorical Yes, No, Partial, Refused
Symptoms and Clinical Course
Fever Categorical Check Box (Y/N/U/R)
Cough Categorical Check Box (Y/N/U/R)
Shortness of Breath Categorical Check Box (Y/N/U/R)
Diarrhea/GI Categorical Check Box (Y/N/U/R)
Headache Categorical Check Box (Y/N/U/R)
Muscle ache Categorical Check Box (Y/N/U/R)
Chills Categorical Check Box (Y/N/U/R)
Sore throat Categorical Check Box (Y/N/U/R)
Vomiting Categorical Check Box (Y/N/U/R)
Abdominal Pain Categorical Check Box (Y/N/U/R)
Nasal congestion Categorical Check Box (Y/N/U/R)
Loss of sense of smell Categorical Check Box (Y/N/U/R)
Loss of sense of taste Categorical Check Box (Y/N/U/R)
Malaise Categorical Check Box (Y/N/U/R)
Fatigue Categorical Check Box (Y/N/U/R)
Other symptom Categorical
Other symptom description Open Text
Date of symptom onset Date
SARS-CoV-2 testing Categorical Check Box (Y/N/U/R)
Date of first SARS-CoV-2 test Date
Results of first SARS-CoV-2 test Categorical Pos/Neg/Equi/Unk
Date of last SARS-CoV-2 test Date
Results of last SARS-CoV-2 test Categorical Pos/Neg/Equi/Unk
Hospitalized Categorical Yes, No, Partial, Refused
Pneumonia Categorical Yes, No, Partial, Refused
ECMO
ICU Categorical Yes, No, Partial, Refused
Death Categorical Yes, No, Partial, Refused
Stroke Categorical Yes, No, Partial, Refused
MI Categorical Yes, No, Partial, Refused
Pre-existing conditions
Chronic lung disease Categorical Yes, No, Partial, Refused
Diabetes Categorical Yes, No, Partial, Refused
Severe Obesity (BMI>=40) Categorical Yes, No, Partial, Refused
CVD Categorical Yes, No, Partial, Refused
Chronic renal disease Categorical Yes, No, Partial, Refused
Chronic liver disease Categorical Yes, No, Partial, Refused
Immunocompromised Categorical Yes, No, Partial, Refused
Pregnant (if Female) Categorical Yes, No, Partial, Refused
Risk Factors
Contact with confirmed COVID case Categorical Y/N/U/R
Employed Categorical Yes/No-unemployed/No-retired/No-unable to work/No-student
If employed, what occupation Open text
If employed, what kind of workplace Open text
HCP Categorical Y/N/U/R Work or volunteer in a healthcare setting
If HCP, what kind of setting
Hospital Categorical Check box
Ambulatory care Categorical Check box
EMS/Fire/Law Enforcement/1st responder Categorical Check box
Urgent care Categorical Check box
Long term care Categorical Check box
Hospice Categorical Check box
Name of HCP setting Open Text
Address of HCP setting Open Text
Congregate setting Categorical Y/N/U/R Do you live or work in congregate setting
If Congregate, what kind
Corrections Categorical Check box
Dorm Categorical Check box
Group home Categorical Check box
Multi-family household Categorical Check box
Multi-generational household Categorical Check box
Name of congregate setting Open Text
Address of congregate setting Open Text
Contact Tracing (during contact elicitation window)
Any household contact Categorical Y/N/U/R
Total Number of household contacts Numeric
Can you self-isolate Categorical Y/N/U/R Add in script what this means (use of bedroom and bathroom away from others)
Do you need assistance to self-isolate Categorical Y/N/U/R
Any intimate partners Categorical Y/N/U/R Partners you do not reside with
Total Number of Intimate Partners Numeric
Any other people in close-contact with, including coworkers Categorical Y/N/U/R
Contact Elicitation Investigation
Data Element Type Codes Notes
Index Information Collected on the index
Investigator Open Text Name of investigator
Investigator ID Numeric
Date Assigned for Investigation Date
Index patient ID Numeric Autogenerated
Lot Number Numeric To track clusters
Date of contact elicitation Date
Start date of Contact Elicitation Window Date
End date of Contact Elicitation Window Date
Information about contacts Ask for each identified contact
Contact Last Name Open Text
Contact First Name Open Text
Contact AKA Open Text
Contact Phone 1 Open Text
Contact Phone 2 Open Text
Contact email 1 Open Text
Contact email 2 Open Text
Contact social media handle 1 Open Text Twitter, Grindr, etc.
Contact social media handle 2 Open Text
Contact Address Open Text
Contact setting Check all that apply
Home Check box
School Check box
Day Care Check box
Workplace Check box includes customers/clients/patients and coworkers
Place of Worship Check box
Shelter Check box
Hospital/Medical Care Check box
Travel or Transit Check box
Retail setting Check box includes, supermarkets, gas stations, farmers markets, etc.
Duration of Exposure (minutes) Numeric
Pre-existing conditions If known
Chronic lung disease Categorical Y/N/U/R
Diabetes Categorical Y/N/U/R
Severe Obesity (BMI>=40) Categorical Y/N/U/R
CVD Categorical Y/N/U/R
Chronic renal disease Categorical Y/N/U/R
Chronic liver disease Categorical Y/N/U/R
Immunocompromised Categorical Y/N/U/R
Pregnant (if Female) Categorical Y/N/U/R
Risk Factors If known
HCP Categorical Y/N/U/R Work or volunteer in a healthcare setting
If HCP, what kind of setting
Hospital Categorical Check box
Ambulatory care Categorical Check box
EMT/Fire/1st responder Categorical Check box
Urgent care Categorical Check box
Long term care Categorical Check box
Hospice Categorical Check box
Congregate setting Categorical Y/N/U/R Do you live or work in congregate setting
If Congregate, what kind
Corrections Categorical Check box
Dorm Categorical Check box
Group home Categorical Check box
Multi-family household Categorical Check box
Multi-generational household Categorical Check box
Community Settings
Travel risk Categorical Y/N/U/R Train, plane, public transit
Specify travel Open Text List specific flights, routes, etc.
Workplace Categorical Y/N/U/R
Specify workplace Open Text Specific work locations
Retail Categorical Y/N/U/R
Specify retail Open Text
Large community social event Categorical Y/N/U/R
Specify Open Text
Recreational activity Categorical Y/N/U/R
Specify Open Text
Places of Worship Categorical Y/N/U/R
Specify Open Text
Data Element Type Codes Notes
Contact Investigation
Locating Information
Investigator Open Text Name of investigator
Investigator ID Numeric
Date Assigned for Investigation Date
Index patient ID Numeric Autogenerated
Lot Number Numeric To track clusters
Contact patient ID Numeric
Contact Last Name Open Text
Contact First Name Open Text
Contact Preferred Name Open Text
DOB Date
Gender Categorical M/F/Other/Unk
Primary Language Open Text/Categorical
Interpreter used Categorical Y/N/U/R
Residential Street Address Open
City of Residence Open Text
County of Residence Open Text
State of Residence Open Text
Zip code Numeric
Tribal Affiliation Open Text
Born in the United States Categorical Y/N/U/R
Phone Number 1 Numeric
Phone Number 2 Numeric
Email 1 Open Text
Email 2 Open Text
Ok to Text Categorical Yes, No, Partial, Refused
Ok to Email Categorical Yes, No, Partial, Refused
Race Categorical Check all apply Use Censuspdf iconexternal icon or HHSexternal icon categories
Ethnicity Categorical Check box Use Censuspdf iconexternal icon or HHSexternal icon categories
Date of interview Attempt 1 Date
Interview 1 occurred Categorical Yes, No, Partial, Refused
Date of interview Attempt 2 Date
Interview 2 occurred Categorical Yes, No, Partial, Refused
Date of interview Attempt 3 Date
Interview 3 occurred Categorical Yes, No, Partial, Refused
Any household contact Categorical Y/N/U/R
Total Number of household contacts Numeric
Can you self-isolate Categorical Y/N/U/R Add in script what this means (use of bedroom and bathroom away from others)
Do you need assistance to self-isolate Categorical Y/N/U/R
Symptoms and Clinical Course
Fever Categorical Check Box (Y/N/U/R)
Cough Categorical Check Box (Y/N/U/R)
Shortness of Breath Categorical Check Box (Y/N/U/R)
Diarrhea/GI Categorical Check Box (Y/N/U/R)
Headache Categorical Check Box (Y/N/U/R)
Muscle ache Categorical Check Box (Y/N/U/R)
Chills Categorical Check Box (Y/N/U/R)
Sore throat Categorical Check Box (Y/N/U/R)
Vomiting Categorical Check Box (Y/N/U/R)
Abdominal Pain Categorical Check Box (Y/N/U/R)
Nasal congestion Categorical Check Box (Y/N/U/R)
Loss of sense of smell Categorical Check Box (Y/N/U/R)
Loss of sense of taste Categorical Check Box (Y/N/U/R)
Other symptom Categorical
Other symptom description
Date of symptom onset Date
SARS-CoV-2 testing Categorical Check Box (Y/N/U/R)
Date of first SARS-CoV-2 test Date
Results of first SARS-CoV-2 test Categorical Pos/Neg/Equi/Unk
Date of last SARS-CoV-2 test Date
Results of last SARS-CoV-2 test Categorical Pos/Neg/Equi/Unk
Pre-existing conditions
Chronic lung disease Categorical Yes, No, Partial, Refused
Diabetes Categorical Yes, No, Partial, Refused
Severe Obesity (BMI>=40) Categorical Yes, No, Partial, Refused
CVD Categorical Yes, No, Partial, Refused
Chronic renal disease Categorical Yes, No, Partial, Refused
Chronic liver disease Categorical Yes, No, Partial, Refused
Immunocompromised Categorical Yes, No, Partial, Refused
Pregnant (if Female) Categorical Yes, No, Partial, Refused
Risk Factors
Contact with confirmed COVID case Categorical Y/N/U/R
Employed Categorical Yes/No-unemployed/No-retired/No-unable to work/No-student
If employed, what occupation Open text
If employed, what kind of workplace Open text
HCP Categorical Y/N/U/R Work or volunteer in a healthcare setting
If HCP, what kind of setting
Hospital Categorical Check box
Ambulatory care Categorical Check box
EMS/Fire/Law Enforcement/1st responder Categorical Check box
Urgent care Categorical Check box
Long term care Categorical Check box
Hospice Categorical Check box
Name of HCP setting Open Text
Address of HCP setting Open Text
Congregate setting Categorical Y/N/U/R Do you live or work in congregate setting
If Congregate, what kind
Corrections Categorical Check box
Dorm Categorical Check box
Group home Categorical Check box
Multi-family household Categorical Check box
Multi-generational household Categorical Check box
Name of congregate setting Open Text
Address of congregate setting Open Text
Appendix D – Tool for Estimating the Number of Contact Tracers Needed

Once states have lower COVID-19 case rates for at least 14 days, widely available testing, and adequate medical/hospital resources, contact tracing becomes an important strategy to eliminate transmission of SARS-CoV-2, the virus that causes COVID-19.  Contact tracing involves multiple steps, including case investigation of COVID-19 clients, notification of close contacts, and daily monitoring of close contacts. This process can be labor-intensive, and communities have different circumstances that affect contact tracing activities. These factors include the number of persons diagnosed with COVID-19 each day, number of contacts per patient, and the amount of time and resources needed to reach and follow the clients and contacts. The number of contact tracers needed is large and will vary by community. Each community will need to examine local case load and other factors to estimate how many contact tracers will be needed.

Mathematical modeling tools can be used to help estimate the number of contact tracers needed. These models require data to quantify each part of the process. The data used may differ among communities and over the course of the pandemic, which may lead to large differences in estimates from different models – or from the same model if using different values. Each community will need to determine some key parameters to be in the model. Local tuberculosis / sexually transmitted disease contact tracers are likely familiar with community-specific “inputs” regarding the average number of contacts per case and how difficult contacts are to find.

CDC does not endorse the use of a specific model; however, these tools may be used to guide planning and calculate resources needed under different scenarios. Each community should carefully incorporate as much knowledge about its situation as possible to estimate the number of contact tracers needed.

Content describing non-CDC tools in this document is provided for informational purposes only and is not intended to indicate endorsement, actual or implied, of the tools. Additionally, information on this site is provided “as is,” for users to evaluate and make their own determination as to their effectiveness.

Example using an available tool: Contact Tracing Staffing Tool – Resolve to Save Livesexternal icon

This model is built into an Excel workbook and requires input on the following values:

  • # new COVID-19 clients / day
  • # close contacts / COVID-19 patient
  • Proportion of clients who are easy / hard / hardest to reach (and never reached). The amount of time needed to arrange and conduct the initial interview with the index patient can vary.
    • Average time needed for patient investigation for each patient category
  • Proportion of contacts who are household/easy/hard/hardest to reach (and never reached). Some contacts might live with the patient; other contacts might lack contact information and require fieldwork to identify.
    • Average time spent on contact notification for each contact category
  • Proportion of clients who can be followed in a mostly automated way versus those who need more staff time. For instance, contacts self-reporting their symptoms via email or text messages require much less time than contacts requiring daily telephone calls.
    • Average amount of time spent on contacts for each day in each category
  • Days spent following contacts (e.g., 14 days after exposure)
  • Staffing considerations:
    • Hours of daily productive work per contact tracer
    • Number of workdays per week per contact tracer
    • Number of contact tracers per manager

Changing the parameters in the model will change the estimated total staffing needed, even when keeping the number of daily new COVID-19 patients constant.  (Note that this model does not specify overall population size. The total amount of work is proportional to the number of COVID-19 clients and contacts identified in each community rather than the total number of people living in the community.)

Estimates of contact tracers needed based on different assumptions in the model
Model developed by Resolve to Save Lives Assumed daily COVID-19 Incidence/ 100,000 persons Contact tracing staff needed / 100,000 persons Notes or assumptions
Contact Tracing Staffing Calculator -Lower estimate (See below) 9* 33 5 contacts per patient; contact tracers work 8 hours/day; contacts easy-to-reach; many contacts use app/email to report daily.
Contact Tracing Staffing Calculator – Higher estimate (See below) 136** 3,739 20 contacts per patient; contact tracers work 7-hour days; contacts harder to reach, take longer to interview, most require calls each day.

*Between April 15-23, 2020, the daily incidence of COVID-19 in the United States ranged between approximately 8 and 9 per 100,000 (between 25,858 and 29,916 new COVID-19 patients per day; assume US population of 328M).

**Approximate peak daily incidence of COVID-19 in New York City (approx. 11,400 incident new patients on 4/15/2020, assume NYC population of 8.4M).

Additional Considerations for Estimating Contact Tracing Resources

There are numerous factors that could affect contact tracer staffing needs that should be accounted for when estimating contact tracer needs:

  • These estimates do not necessarily include all managers or additional professions needed.
  • Increased case finding and testing efforts, as well as relaxing mobility restrictions could lead to more daily COVID-19 clients and/or contacts, which would require tracing resources.
  • Effective contact tracing could reduce the number of new COVID-19 clients and contacts over time.
  • Time from diagnosis to isolation for the index patient with COVID-19 will affect the number of contacts exposed and needing follow-up.
  • Use of digital contact tracing toolspdf icon could improve workflow efficiency or allow automated messages/contact self-report of symptoms to save contact tracer effort.
  • These models do not necessarily apply to special populations such as people in prisons or long-term care facilities.

This information will be updated as more tools become available.

Parameter values used for high and low estimates

(these are for illustrative purposes only)

Low Estimate Values—daily incident cases based on approximate average national daily incidence

Low Estimate Values—daily incident cases based on approximate average national daily incidence

High Estimate Values—daily incident cases based on peak daily incidence from NYC (approx. 11,400 cases among 8.4M persons)

High Estimate Values—daily incident cases based on peak daily incidence from NYC (approx. 11,400 cases among 8.4M persons)