Early Epidemiological Evidence of Public Health Value of WA Notify, a Smartphone-based Exposure Notification Tool: Modeling COVID-19 Cases Averted in Washington State
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Abstract
Background
Secure and anonymous smartphone-based exposure notification tools are recently developed public health interventions that aim to reduce COVID-19 transmission and supplement traditional public health suriveillance. We assessed the impact of Washington State’s exposure notification tool, WA Notify, in mitigating the spread of COVID-19 during its first four months of implementation.
Methods
Due to the constraints of privacy-preservation, aggregate metrics and disparate data sources were utilized to estimate the number of COVID-19 cases averted based on a modelling approach adapted from Wymant et al (2021) using the following parameters: number of notifications generated; the probability that a notified individual goes on to become a case; expected fraction of transmissions preventable by strict quarantine after notification; actual adherence to quarantine; and expected size of the full transmission chain if a contact had not been notified.
Results
The model was run on a range of secondary attack rates (5.1%-13.706%) and quarantine effectiveness (53% and 64%). Assuming a 12.085% secondary attack rate and 53% quarantine effectiveness, the model shows that 5,500 cases (central 95% range of sensitivity analyses 2,800-8,200) were averted statewide during the first four months of its implementation. Based on an estimated COVID-19 case fatality of 1.4%, WA Notify saved 40-115 lives during the study period.
Conclusions
These findings demonstrate the value of exposure notification tools as a novel public health intervention to mitigate the spread of COVID-19 in the U.S. As new variants emerge and non-essential travel bans are lifted, exposure notification tools may continue to play a valuable role in limiting the spread of COVID-19.
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SciScore for 10.1101/2021.06.04.21257951: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: The UW Institutional Review Board reviewed the evaluation plan, and determined it was a public health quality improvement project and non-human subjects research. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. 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:As an anonymous, privacy-preserving tool there are limitations to understanding the userbase and how …
SciScore for 10.1101/2021.06.04.21257951: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: The UW Institutional Review Board reviewed the evaluation plan, and determined it was a public health quality improvement project and non-human subjects research. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. 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:As an anonymous, privacy-preserving tool there are limitations to understanding the userbase and how the tool may motivate users to engage in protective behaviors20. Our use of aggregate metrics from available public and de-identified data sources presents one strategy for conducting future evaluations that could examine additional impacts of WA Notify21. Further investigation into the user experience through surveys as well as the reach and timeliness of WA Notify compared to traditional CI/CT is warranted to improve our understanding of its impact on collective public health efforts. GAEN represents a private-public partnership in technology to scale the communication of risk notification and supplement the tools PHAs have to support their communities for the control of infectious diseases. The partnership with private sector technology providers (Google, Apple and Microsoft) has resulted in a remarkable rapid transformation of a methodology from concept into large scale practice22. This includes the collaboration on both the creation of the API and the transition from custom application towards a more rapidly adopted shared technology EN Express23. EN systems are just one tool among many (vaccines, CI/CT, masks, hygiene, social distancing, occupancy policies) that should be leveraged to contain the spread of COVID-19, and with the expanding evidence-base for their effectiveness, integrating tools like WA Notify into public health practice alongside other established interv...
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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