Snowball: Network-Targeted Strategies for Efficient Community SARS-CoV-2 (COVID-19) Sampling

Duke University (Other)
Overall Status
Enrolling by invitation ID
Anticipated Duration (Months)
Patients Per Site Per Month

Study Details

Study Description

Brief Summary

The primary objective is to use "network targeted sampling design" to detect active and/or undiagnosed cases of COVID-19 in the community and determine the spread or distribution of 1) active infection, and 2) past exposure. The hypothesis is that there are many undiagnosed and/or asymptomatic people in the community who may be unknowingly spreading the virus or have been exposed and have antibodies. We propose to implement respondent-driven sampling (RDS) which leverages effort on the part of seed or index cases to recruit contacts for participation.

Condition or DiseaseIntervention/TreatmentPhase

    Detailed Description

    Purpose and objective: The purpose of this study is to use community sampling to detect active, undiagnosed COVID-19 cases and/or determine the spread or distribution of active infection. The objective is to use a network targeted sampling design to direct testing to yield a higher proportion of results which indicate active infection and possibly differentiating between venues or communities where transmission is active and undiagnosed.

    Study activities: A person who tests positive for COVID-19 will be given a set of "tokens" to give to contacts that will entitle these contacts to make an appointment to receive a test for COVID-19.

    Population groups: The population group will include people with index cases of COVID-19 and their contacts for the past 14 days. As these contacts are tested and receive positive results, they will be given tokens to hand out to their contacts over the past 14 days. The network of positive cases will "blossom" to reveal community transmission and asymptomatic cases, thus giving researchers an indication of disease prevalence.

    Data analysis: At the completion of each epoch and at the end of the study, we will scale the social networks up and conduct network analysis using SAS and the igraph package in R. These analyses will be applied in an ongoing manner to guide selection of seeds in subsequent epochs to ensure representativeness and to guide selection of alters to encourage longer referral chain lengths.

    Risk/safety issues: The primary risks include discomfort from the nasal swab and risks from the venous blood draw used in testing and the potential loss of confidentiality. All efforts will be made to securely manage the data to ensure participant confidentiality.

    Study Design

    Study Type:
    Anticipated Enrollment :
    200 participants
    Observational Model:
    Ecologic or Community
    Time Perspective:
    Official Title:
    Network-Targeted Strategies for Efficient Community SARS-CoV-2 (COVID-19) Sampling
    Actual Study Start Date :
    Dec 11, 2020
    Anticipated Primary Completion Date :
    Jun 30, 2022
    Anticipated Study Completion Date :
    Jun 30, 2022

    Arms and Interventions


    Participants completing COVID-19 testing

    Outcome Measures

    Primary Outcome Measures

    1. Number of Participants with Active Infection [12 months]

      Number of participants with active COVID-19 infection

    2. Number of Participants with Antibodies Indicating Past Exposure [12 months]

      Number of participants with antibodies indicating past exposure to SARS-CoV-2

    Eligibility Criteria


    Ages Eligible for Study:
    18 Years and Older
    Sexes Eligible for Study:
    Accepts Healthy Volunteers:
    Inclusion Criteria:
    • Positive COVID-19 test result -or- receipt of a coupon from a previous study participant

    • Resident of Durham County (for seed participant only)

    • Willing to undergo COVID-19 test nasopharyngeal swab for RT-PCR testing and blood draw for COVID-19 antibody testing

    • Age 18+

    • Speak and understand English

    Exclusion Criteria:
    • Currently receiving inpatient treatment for COVID-19

    • Unable to consent

    Contacts and Locations


    SiteCityStateCountryPostal Code
    1Margaret PendzichDurhamNorth CarolinaUnited States27710

    Sponsors and Collaborators

    • Duke University


    • Principal Investigator: Dana Pasquale, PhD, Duke University

    Study Documents (Full-Text)

    None provided.

    More Information


    None provided.
    Responsible Party:
    Duke University Identifier:
    Other Study ID Numbers:
    • Pro00105430
    First Posted:
    Jun 18, 2020
    Last Update Posted:
    Nov 18, 2021
    Last Verified:
    Nov 1, 2021
    Individual Participant Data (IPD) Sharing Statement:
    Plan to Share IPD:
    Studies a U.S. FDA-regulated Drug Product:
    Studies a U.S. FDA-regulated Device Product:
    Keywords provided by Duke University
    Additional relevant MeSH terms:

    Study Results

    No Results Posted as of Nov 18, 2021