Digital measurement of SARS-CoV-2 transmission risk from 7 million contacts
How likely is it to become infected by SARS-CoV-2 after being exposed? Almost everyone wondered about this question during the COVID-19 pandemic. Contact-tracing apps1,2 recorded measurements of proximity3 and duration between nearby smartphones. Contacts—individuals exposed to confirmed cases—were...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
Springer Nature
2023
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| _version_ | 1811139747461988352 |
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| author | Ferretti, L Wymant, C Petrie, J Tsallis, D Kendall, M Ledda, A Di Lauro, F Fowler, A Di Francia, A Abeler-Dörner, L Charalambides, M Briers, M Fraser, C |
| author_facet | Ferretti, L Wymant, C Petrie, J Tsallis, D Kendall, M Ledda, A Di Lauro, F Fowler, A Di Francia, A Abeler-Dörner, L Charalambides, M Briers, M Fraser, C |
| author_sort | Ferretti, L |
| collection | OXFORD |
| description | How likely is it to become infected by SARS-CoV-2 after being exposed? Almost everyone wondered about this question during the COVID-19 pandemic. Contact-tracing apps1,2 recorded measurements of proximity3 and duration between nearby smartphones. Contacts—individuals exposed to confirmed cases—were notified according to public health policies such as the 2 m, 15 min guideline4,5, despite limited evidence supporting this threshold. Here we analysed 7 million contacts notified by the National Health Service COVID-19 app6,7 in England and Wales to infer how app measurements translated to actual transmissions. Empirical metrics and statistical modelling showed a strong relation between app-computed risk scores and actual transmission probability. Longer exposures at greater distances had risk similar to that of shorter exposures at closer distances. The probability of transmission confirmed by a reported positive test increased initially linearly with duration of exposure (1.1% per hour) and continued increasing over several days. Whereas most exposures were short (median 0.7 h, interquartile range 0.4–1.6), transmissions typically resulted from exposures lasting between 1 h and several days (median 6 h, interquartile range 1.4–28). Households accounted for about 6% of contacts but 40% of transmissions. With sufficient preparation, privacy-preserving yet precise analyses of risk that would inform public health measures, based on digital contact tracing, could be performed within weeks of the emergence of a new pathogen. |
| first_indexed | 2024-09-25T04:11:00Z |
| format | Journal article |
| id | oxford-uuid:b45de656-a5b1-41a8-a352-12f8c1a4f1ae |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-09-25T04:11:00Z |
| publishDate | 2023 |
| publisher | Springer Nature |
| record_format | dspace |
| spelling | oxford-uuid:b45de656-a5b1-41a8-a352-12f8c1a4f1ae2024-06-21T16:47:42ZDigital measurement of SARS-CoV-2 transmission risk from 7 million contactsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:b45de656-a5b1-41a8-a352-12f8c1a4f1aeEnglishSymplectic ElementsSpringer Nature2023Ferretti, LWymant, CPetrie, JTsallis, DKendall, MLedda, ADi Lauro, FFowler, ADi Francia, AAbeler-Dörner, LCharalambides, MBriers, MFraser, CHow likely is it to become infected by SARS-CoV-2 after being exposed? Almost everyone wondered about this question during the COVID-19 pandemic. Contact-tracing apps1,2 recorded measurements of proximity3 and duration between nearby smartphones. Contacts—individuals exposed to confirmed cases—were notified according to public health policies such as the 2 m, 15 min guideline4,5, despite limited evidence supporting this threshold. Here we analysed 7 million contacts notified by the National Health Service COVID-19 app6,7 in England and Wales to infer how app measurements translated to actual transmissions. Empirical metrics and statistical modelling showed a strong relation between app-computed risk scores and actual transmission probability. Longer exposures at greater distances had risk similar to that of shorter exposures at closer distances. The probability of transmission confirmed by a reported positive test increased initially linearly with duration of exposure (1.1% per hour) and continued increasing over several days. Whereas most exposures were short (median 0.7 h, interquartile range 0.4–1.6), transmissions typically resulted from exposures lasting between 1 h and several days (median 6 h, interquartile range 1.4–28). Households accounted for about 6% of contacts but 40% of transmissions. With sufficient preparation, privacy-preserving yet precise analyses of risk that would inform public health measures, based on digital contact tracing, could be performed within weeks of the emergence of a new pathogen. |
| spellingShingle | Ferretti, L Wymant, C Petrie, J Tsallis, D Kendall, M Ledda, A Di Lauro, F Fowler, A Di Francia, A Abeler-Dörner, L Charalambides, M Briers, M Fraser, C Digital measurement of SARS-CoV-2 transmission risk from 7 million contacts |
| title | Digital measurement of SARS-CoV-2 transmission risk from 7 million contacts |
| title_full | Digital measurement of SARS-CoV-2 transmission risk from 7 million contacts |
| title_fullStr | Digital measurement of SARS-CoV-2 transmission risk from 7 million contacts |
| title_full_unstemmed | Digital measurement of SARS-CoV-2 transmission risk from 7 million contacts |
| title_short | Digital measurement of SARS-CoV-2 transmission risk from 7 million contacts |
| title_sort | digital measurement of sars cov 2 transmission risk from 7 million contacts |
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