Measuring the scientific effectiveness of contact tracing: Evidence from a natural experiment

Fetzer, Thomas; Graeber, Thomas

doi:10.1073/pnas.2100814118

Cited by 80 publications

(69 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The reason lies in the fact that a substantial share of these tests is driven by an elevated probability to carry the virus, i.e., showing symptoms of CoViD-19 or following up on a positive test of a household member. The latter is essentially a form of contact tracing, which has been shown to be very effective 2 , 25 , 26 . Indeed, a deeper analysis in Supplementary Material B.15 shows that the same amount of rapid tests administered randomly in the population would not have been nearly as effective.…”

Section: Resultsmentioning

confidence: 99%

The effectiveness of testing, vaccinations and contact restrictions for containing the CoViD-19 pandemic

Gabler

Raabe

Röhrl

et al. 2022

Sci Rep

View full text Add to dashboard Cite

In order to slow the spread of the CoViD-19 pandemic, governments around the world have enacted a wide set of policies limiting the transmission of the disease. Initially, these focused on non-pharmaceutical interventions; more recently, vaccinations and large-scale rapid testing have started to play a major role. The objective of this study is to explain the quantitative effects of these policies on determining the course of the pandemic, allowing for factors like seasonality or virus strains with different transmission profiles. To do so, the study develops an agent-based simulation model, which explicitly takes into account test demand and behavioral changes following positive tests. The model is estimated using data for the second and the third wave of the CoViD-19 pandemic in Germany. The paper finds that during a period where vaccination rates rose from 5 to 40%, seasonality and rapid testing had the largest effect on reducing infection numbers. Frequent large-scale rapid testing should remain part of strategies to contain CoViD-19; it can substitute for many non-pharmaceutical interventions that come at a much larger cost to individuals, society, and the economy.

show abstract

Section: Resultsmentioning

confidence: 99%

The effectiveness of testing, vaccinations and contact restrictions for containing the CoViD-19 pandemic

Gabler

Raabe

Röhrl

et al. 2022

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Importantly, ( 4 ) showed - using genome sequence data - that New Zealand contact tracing was highly effective in identifying SARS-CoV-2 infection clusters. Then, ( 25 ) recently exploited an accidental, partial breakdown of English contact tracing to show that normal contact tracing in early fall 2020 reduced transmissions by 63% in the 6 weeks following a positive case. This measure is within the range of our estimates for a transmission slowdown in Switzerland in summer 2020.…”

Section: Discussionmentioning

confidence: 99%

Swiss public health measures associated with reduced SARS-CoV-2 transmission using genome data

Nadeau

Vaughan

Beckmann³

et al. 2021

Preprint

View full text Add to dashboard Cite

Genome sequences allow quantification of changes in case introductions from abroad and local transmission dynamics. We sequenced 11,357 SARS-CoV-2 genomes from Switzerland in 2020 - the 6th largest effort globally. Using these data, we estimated introductions and their persistence throughout 2020. By contrasting estimates with null models, we estimate at least 83% of introductions were adverted during Switzerland’s border closures. Further, transmission chain persistence roughly doubled after the partial lockdown was lifted. Then, using a novel phylodynamic method, we suggest transmission in newly introduced outbreaks slowed 36 - 64% upon outbreak detection in summer 2020, but not in fall. This could indicate successful contact tracing over summer before overburdening in fall. The study highlights the added value of genome sequencing data for understanding transmission dynamics.

show abstract

“…To limit COVID-19 person-to-person transmission and slow the spread of the virus, various control measures are indicated: raise awareness on healthy behavior, detecting cases, detecting contacts, isolation and quarantine, infection control practice in health facilities, social measures, vaccination… Despite being in in the context of community transmission, the contact tracing is still valid option to slow down the epidemic curve and reduce mortality burden (4, 5, 6).…”

Section: Background and Objectivementioning

confidence: 99%

COVID-19 contact tracing during first delta wave, Lebanon, 2021

Baakliny

Naim

Hage

et al. 2022

Preprint

View full text Add to dashboard Cite

Background On the 11th March, the WHO has declared COVID-19 pandemic. Officially, the virus was introduced in Lebanon on the 21st February 2020. Since then, the national curve has drawn several waves. From July to September 2021, Lebanon has experienced the first delta wave. As part of the investigation, contact tracing was enhanced to limit virus transmission. The objective is to describe close tracing approach and profile of close contacts identified during the first delta wave. Methods COVID-19 surveillance is integrated within the national communicable diseases surveillance. The case definitions are adopted from WHO guides. Laboratories report positive cases on daily basis to the Ministry of Public Health, on DHIS2 platform directly or indirectly via excel files importation. Once reported, case investigation is initiated. It includes contact tracing with: 1) identification of close contacts, 2) advice on quarantine and self-monitoring, 3) contact testing. Referral to field testing is made available free of charge for close contacts. Collected data is updated on DHIS2 platform. Later, data is cleaned and analyzed to generate the daily report including description of close contacts. The report is shared with decision makers, professionals, media and public. Results From week 2021W27 to week 2021W40, 85490 cases were reported. Case investigation rate reached 78.8% of the cases were investigated within 24 hours. 66.5% of investigated cases shared lists of contacts, with 3.6 as average number of contacts per case. We identified a total of 161805 close contacts, 95% were from family members, 71% were not vaccinated and 10 % had prior COVID-19 infection. As for contact testing, 65% had RT-PCR test upon investigation, with 32% positive result. Furthermore, 19205 were referred and tested via field testing, with 25% positivity rate. Of all identified contacts, the reported positive tests reached 56,904 representing 35.2% of all contacts. Conclusion During community transmission and mitigation strategy, contact tracing contributes to increase awareness to the contacts and importance to abide to quarantine measures and thus to slow down the virus circulation. Current close contacts are characterized with new profile of prior infection, vaccination history and testing behavior. There is need to adapt the quarantine measures to close contacts based on their profile, and to ensure easy access to free testing.

show abstract

Measuring the scientific effectiveness of contact tracing: Evidence from a natural experiment

Cited by 80 publications

References 17 publications

The effectiveness of testing, vaccinations and contact restrictions for containing the CoViD-19 pandemic

The effectiveness of testing, vaccinations and contact restrictions for containing the CoViD-19 pandemic

Swiss public health measures associated with reduced SARS-CoV-2 transmission using genome data

COVID-19 contact tracing during first delta wave, Lebanon, 2021

Contact Info

Product

Resources

About