Estimates of Cases and Hospitalizations Averted by COVID-19 Case Investigation and Contact Tracing in 14 Health Jurisdictions in the United States

  1. Seonghye Jeon
  2. Gabriel Rainisch
  3. R. Ryan Lash
  4. Patrick K. Moonan
  5. John E. Oeltmann
  6. Bradford Greening
  7. Bishwa B. Adhikari
  8. Martin I. Meltzer

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Abstract

The implementation of case investigation and contact tracing (CICT) for controlling COVID-19 (caused by SARS-CoV-2 virus) has proven challenging due to varying levels of public acceptance and initially constrained resources, especially enough trained staff. Evaluating the impacts of CICT will aid efforts to improve such programs.

Objectives:

Estimate the number of COVID-19 cases and hospitalizations averted by CICT and identify CICT processes that could improve overall effectiveness.

Design:

We used data on the proportion of cases interviewed, contacts notified or monitored, and days from testing to case and contact notification from 14 jurisdictions to model the impact of CICT on cumulative case counts and hospitalizations over a 60-day period. Using the Centers for Disease Control and Prevention's COVIDTracer Advanced tool, we estimated a range of impacts by assuming either contacts would quarantine only if monitored or would do so upon notification of potential exposure. We also varied the observed program metrics to assess their relative influence.

Results:

Performance by jurisdictions varied widely. Jurisdictions isolated between 12% and 86% of cases (including contacts that became cases) within 6 to 10 days after infection. We estimated that CICT-related reductions in transmission ranged from 0.4% to 32%. For every 100 remaining cases after other nonpharmaceutical interventions were implemented, CICT averted between 4 and 97 additional cases. Reducing time to case isolation by 1 day increased averted case estimates by up to 15 percentage points. Increasing the proportion of cases interviewed or contacts notified by 20 percentage points each resulted in at most 3 or 6 percentage point improvements in averted cases.

Conclusions:

We estimated that CICT reduced the number of COVID-19 cases and hospitalizations among all jurisdictions studied. Reducing time to isolation produced the greatest improvements in impact of CICT.

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  1. Version published to 10.1097/phh.0000000000001420
  2. ScreenIT

    SciScore for 10.1101/2021.05.27.21257931: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    This study also has several limitations. First, we did not directly measure the proportions of cases that effectively isolated and contacts that correctly quarantined. In the absence of data suggesting otherwise, we assumed cases and contacts fully comply with isolation and quarantine guidance they received via their interactions with health departments. As such, our results may overestimate the absolute impact of CICT (and underestimate the effectiveness of NPIs), with our lower effectiveness results likely approximating real impacts more closely. Our conclusions, however, regarding the relative influence of CICT measures are not affected by this limitation. Additionally, our maximum estimates of effectiveness offer insight into the potential benefits from high public compliance with quarantine guidance. Nevertheless, there is obvious need for additional research to improve our understanding of the actual efficacy of isolation and quarantine, based on public compliance, the role of health departments in motivating such, as well as practical limitations (e.g., inadequate sick leave, caregiving responsibilities). Lastly, we do not know whether Exposure Notification (EN) Apps (i.e., smartphone-enabled contact tracing apps) were utilized by locations during the observation period we analyzed, and if so, how their use would have affected our results. A second limitation is we assumed that the effectiveness of CICT and NPIs remained constant over a 60-day period. Since we were abl...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

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  3. Version published to 10.1101/2021.05.27.21257931v1 on medRxiv