Empirical evidence on the efficiency of bidirectional contact tracing in COVID-19

Raymenants, Joren; Geenen, Caspar; Nelissen, None; Gorissen, Sarah; André, Emmanuel

doi:10.21203/rs.3.rs-952839/v1

Cited by 3 publications

(4 citation statements)

References 25 publications

(37 reference statements)

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“…This retrospective case-ascertained study was performed on data gathered in the context of a testing and contact tracing system targeted to over 30.000 tertiary education students in Leuven, Belgium [12,13]. A standard screening protocol for student residences was introduced on October 30th 2020 and aimed to strike a balance between effectiveness and proportionality (Fig.…”

Section: Setting and Designmentioning

confidence: 99%

Risk factors for SARS-CoV-2 transmission in student residences: a case-ascertained study

et al. 2022

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Background We aimed to investigate the overall secondary attack rates (SAR) of COVID-19 in student residences and to identify risk factors for higher transmission. Methods We retrospectively analysed the SAR in living units of student residences which were screened in Leuven (Belgium) following the detection of a COVID-19 case. Students were followed up in the framework of a routine testing and tracing follow-up system. We considered residence outbreaks followed up between October 30th 2020 and May 25th 2021. We used generalized estimating equations (GEE) to evaluate the impact of delay to follow-up, shared kitchen or sanitary facilities, the presence of a known external infection source and the recent occurrence of a social gathering. We used a generalized linear mixed model (GLMM) for validation. Results We included 165 student residences, representing 200 residence units (N screened residents = 2324). Secondary transmission occurred in 68 units which corresponded to 176 secondary cases. The overall observed SAR was 8.2%. In the GEE model, shared sanitary facilities (p = 0.04) and the recent occurrence of a social gathering (p = 0.003) were associated with a significant increase in SAR in a living unit, which was estimated at 3% (95%CI 1.5-5.2) in the absence of any risk factor and 13% (95%CI 11.4-15.8) in the presence of both. The GLMM confirmed these findings. Conclusions Shared sanitary facilities and the occurrence of social gatherings increase the risk of COVID-19 transmission and should be considered when screening and implementing preventive measures.

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Section: Setting and Designmentioning

confidence: 99%

Risk factors for SARS-CoV-2 transmission in student residences: a case-ascertained study

et al. 2022

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“…This retrospective case-ascertained study was performed on data gathered in the context of a testing and contact tracing system targeted to over 30.000 tertiary education students in Leuven, Belgium 12,13 . A standard screening protocol for student residences was introduced on October 30 th 2020 and aimed to strike a balance between effectiveness and proportionality (figure 1).…”

Section: Setting and Designmentioning

confidence: 99%

Risk factors for SARS-CoV-2 transmission in student residences: a case-ascertained study in Leuven, Belgium from October 2020 until May 2021

Vanbesien

Molenberghs

Geenen

et al. 2022

Preprint

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Background Student residences are at high risk for rapid COVID-transmission due to crowding and frequent close contact. Aim We aimed to investigate the overall secondary attack rates (SAR) in student residences and to discern risk factors for higher transmission in order to improve the evidence base for screening efforts and preventive measures. Methods In this retrospective case-ascertained study, we analysed data from student residences screened in Leuven, Belgium between October 2020 and May 2021, following detection of a COVID-19 case in the residence. We investigated the impact on the SAR in the living units screened of delay-time until follow-up, shared use of kitchen or sanitary facilities, presence of an external infection source and occurrence of social gatherings attended by the index case. Results We included 200 residence units, representing 2326 screened residents, of which 68 units showed secondary transmission. The overall SAR was estimated at 0.0813 (95%CI 0.0705-0.0936). Both sharing sanitary facilities (p=0.04) and social gatherings attended by the index case (p=0.033) significantly impacted SAR, which increased from 3% to 13% when both risk factors were present compared to absent. Conclusions We identify risk factors which should be considered when selecting students for screening during an outbreak of COVID-19 in student residences to improve comprehensiveness and proportionality of testing. The identified risk factors improve the evidence base for preventive measures aimed at limiting social gatherings and improving ventilation of shared spaces in outbreak-prone settings. Lastly, they should be considered when designing student accommodation and other shared households.

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“…Bidirectional contact tracing combines forward contact tracing and backward contact tracing. Forward contact tracing of an index case (the person diagnosed with COVID-19 undergoing contact tracing) intends to interrupt onward transmission from child cases (persons infected by the index case) 15,[22][23][24] . In practice, this means identifying contacts of the index case up to two days before symptom onset or positive test, whichever is earlier 25,26 .…”

Section: Implement An Extended Contact Tracing Windowmentioning

confidence: 99%

“…In practice, this means identifying contacts of the index case up to two days before symptom onset or positive test, whichever is earlier 25,26 . Backward contact tracing attempts to identify a larger part of the transmission tree, by looking for the parent case (the infector of the index case) and sibling cases (infected by the same infector) in addition 15,[22][23][24] . However, to our knowledge there is no standardised protocol on how to achieve this.…”

Section: Implement An Extended Contact Tracing Windowmentioning

confidence: 99%

Integrated PCR testing and extended window contact tracing system for COVID-19 to improve comprehensiveness and speed

Raymenants¹,

Geenen²,

Thibaut³

et al. 2021

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Testing and contact tracing are standard tools for controlling the spread of COVID-191. Their effectiveness hinges on a sequence of processes encompassing testing coverage and timeliness, testing quality and speed of reporting, contact tracing speed and comprehensiveness and compliance with advice given2–6. We optimized this sequence of processes in the context of a public health program targeting around 33,000 higher education students through a combination of low barrier PCR testing with rapid turn-around-time, close integration of testing and tracing teams and IT infrastructure, community engagement and the implementation of bidirectional contact tracing by extending the contact tracing window from 2 to 7 days before symptom onset or test of the index case. We anticipate this combined intervention to help improve epidemic control.

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Empirical evidence on the efficiency of bidirectional contact tracing in COVID-19

Cited by 3 publications

References 25 publications

Risk factors for SARS-CoV-2 transmission in student residences: a case-ascertained study

Risk factors for SARS-CoV-2 transmission in student residences: a case-ascertained study

Risk factors for SARS-CoV-2 transmission in student residences: a case-ascertained study in Leuven, Belgium from October 2020 until May 2021

Integrated PCR testing and extended window contact tracing system for COVID-19 to improve comprehensiveness and speed

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