8/7—Effective Contact Tracing for COVID-19: A Systematic Review
This is a preprint I wrote with colleagues. For a media report, see Quebec needs to streamline COVID testing and contact tracing: scientist. A total of 32 articles were found. All were observational or modelling studies, so the quality of the evidence was low. A cautious interpretation suggests that to stop the spread of COVID-19, public health practitioners have 2-3 days from the time a new case develops symptoms to isolate the case and quarantine at least 80% of its contacts, and that once isolated, cases and contacts should infect zero new cases. Less efficient tracing may slow, but not stop, the spread of COVID-19. Inefficient tracing (with delays of 4-5+ days or less than 60% of contacts quarantined with no further transmission) may not contribute meaningfully to control of COVID-19 (Juneau et al. 2020).
Characteristics and Outcomes of Contacts of COVID-19 Patients Monitored Using an Automated Symptom Monitoring Tool — Maine, May–June 2020
Maine found that using automated symptom monitoring as a part of the state’s contact tracing program was well received, with the majority of monitored contacts (96.4%) agreeing to automated symptom monitoring. Automated symptom monitoring promptly identified COVID-19 diagnoses among monitored contacts. Among 1,622 persons enrolled into an automated symptom monitoring system, 190 (11.7%) developed COVID-19. Prompt case investigation can rapidly identify contacts and recommend quarantine, reducing additional exposures and transmission.
An increasing public health burden arising from children infected with SARS‐CoV2: a systematic review and meta‐analysis
We obtained data from 14 eligible studies with 410 patients [children] for the meta‐analysis. The pooled proportion of asymptomatic infection was 40.45% (95%CI: 24.04‐56.85). The pooled proportion of family clustering infection was 83.63% (95%CI: 77.54‐89.72). These data affirm the increasing public health burden arising from infected children regarding the causation of asymptomatic infection […] and as a significant contributor to virus spread.
How can airborne transmission of COVID-19 indoors be minimised?
We argue that existing evidence is sufficiently strong to warrant engineering controls targeting airborne transmission as part of an overall strategy to limit infection risk indoors. Appropriate building engineering controls include sufficient and effective ventilation, possibly enhanced by particle filtration and air disinfection, avoiding air recirculation and avoiding overcrowding. Often, such measures can be easily implemented and without much cost. We believe that the use of engineering controls in public buildings, including hospitals, shops, offices, schools, kindergartens, libraries, restaurants, cruise ships, elevators, conference rooms or public transport […] would be an additional important measure globally to reduce the likelihood of transmission.
Determining the optimal strategy for reopening schools, the impact of test and trace interventions, and the risk of occurrence of a second COVID-19 epidemic wave in the UK: a modelling study
Assuming 68% of contacts could be traced, we estimate that 75% of individuals with symptomatic infection would need to be tested and positive cases isolated if schools return full-time in September, or 65% if a part-time rota system were used. If only 40% of contacts could be traced, these figures would increase to 87% and 75%, respectively. However, without these levels of testing and contact tracing, reopening of schools together with gradual relaxing of the lockdown measures are likely to induce a second wave that would peak in December [if schools open full-time in September].
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