The Kirby Institute, University of New South Wales, Sydney, NSW, Australia; National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT, Australia.
The Kirby Institute, University of New South Wales, Sydney, NSW, Australia.
Lancet Public Health. 2022 Mar;7(3):e250-e258. doi: 10.1016/S2468-2667(22)00010-X. Epub 2022 Feb 4.
Digital proximity tracing apps were rolled out early in the COVID-19 pandemic in many countries to complement conventional contact tracing. Empirical evidence about their benefits for pandemic response remains scarce. We evaluated the effectiveness and usefulness of COVIDSafe, Australia's national smartphone-based proximity tracing app for COVID-19.
In this prospective study, done in New South Wales (NSW), Australia, we included all individuals in the state who were older than 12 years with confirmed, locally acquired SARS-CoV-2 infection between May 4 and Nov 4, 2020. We used data from the NSW Notifiable Conditions Information Management System, the national COVIDSafe database, and information from case interviews, including information on app usage, the number of app-suggested contacts, and the number of app-suggested contacts determined by public health staff to be actual close contacts. We calculated the positive predictive value and sensitivity of COVIDSafe, its additional contact yield, and the number of averted public exposure events. Semi-structured interviews with public health staff were done to assess the app's perceived usefulness.
There were 619 confirmed COVID-19 cases with more than 25 300 close contacts identified by conventional contact tracing during the study period. COVIDSafe was used by 137 (22%) cases and detected 205 contacts, 79 (39%) of whom met the close contact definition. Its positive predictive value was therefore 39%. 35 (15%) of the 236 close contacts who could have been expected to have been using the app during the study period were identified by the app, making its estimated sensitivity 15%. 79 (0·3%) of the estimated 25 300 contacts in NSW were app-suggested and met the close contact definition. The app detected 17 (<0·1%) additional close contacts who were not identified by conventional contact tracing. COVIDSafe generated a substantial additional perceived workload for public health staff and was not considered useful.
The low uptake of the app among cases probably led to a reduced sensitivity estimate in our study, given that only contacts who were using the app could be detected. COVIDSafe was not sufficiently effective to make a meaningful contribution to the COVID-19 response in Australia's most populous state over a 6 month period. We provide an empirical evaluation of this digital contact tracing app that questions the potential benefits of digital contact tracing apps to the public health response to COVID-19. Effectiveness evaluations should be integrated into future implementations of proximity contact tracing systems to justify their investment.
New South Wales Ministry of Health (Australia); National Health and Medical Research Council (Australia).
在许多国家，新冠疫情早期推出了数字近距离追踪应用程序，以补充传统的接触者追踪。有关其对大流行应对的益处的经验证据仍然很少。我们评估了澳大利亚全国基于智能手机的 COVIDSafe 应用程序在 COVID-19 中的有效性和实用性。
在澳大利亚新南威尔士州（新州）进行的这项前瞻性研究中，我们纳入了 2020 年 5 月 4 日至 11 月 4 日期间在该州年龄超过 12 岁、确诊、本地获得性 SARS-CoV-2 感染的所有个体。我们使用了新州传染病信息管理系统、全国 COVIDSafe 数据库的数据以及病例访谈信息，包括应用程序使用情况、应用程序建议的接触者数量以及公共卫生工作人员确定的实际密切接触者数量。我们计算了 COVIDSafe 的阳性预测值和敏感性、其额外接触的产生以及避免的公共暴露事件的数量。对公共卫生工作人员进行了半结构化访谈，以评估该应用程序的感知实用性。
在研究期间，通过常规接触者追踪发现 619 例确诊 COVID-19 病例，有超过 25300 名密切接触者。有 137 例（22%）病例使用了 COVIDSafe 应用程序，发现了 205 名接触者，其中 79 名（39%）符合密切接触者的定义。因此，其阳性预测值为 39%。在研究期间预计有 35 名（15%）密切接触者会使用该应用程序，但只有 236 名密切接触者中的 35 名被该应用程序识别，这使其估计敏感性为 15%。在新州，预计有 79（0.3%）名接触者会使用该应用程序，但符合密切接触者的定义。该应用程序发现了 17 名（<0.1%）未通过常规接触者追踪发现的额外密切接触者。COVIDSafe 为公共卫生工作人员带来了大量额外的感知工作量，而且被认为没有用处。
由于只有使用该应用程序的接触者才能被检测到，因此病例中应用程序的低使用率可能导致敏感性估计值降低。在澳大利亚人口最多的州，COVIDSafe 在 6 个月内并没有足够有效，无法对 COVID-19 应对做出有意义的贡献。我们对这种数字接触追踪应用程序进行了实证评估，对数字接触追踪应用程序对 COVID-19 公共卫生应对的潜在益处提出了质疑。应将有效性评估纳入未来的近距离接触追踪系统实施中，以证明其投资的合理性。
新南威尔士州卫生部（澳大利亚）；澳大利亚国家卫生与医学研究理事会（澳大利亚）。
