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Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility
BACKGROUND: After a rapid upsurge of COVID-19 cases in Italy during the fall of 2020, the government introduced a three-tiered restriction system aimed at increasing physical distancing. The Ministry of Health, after periodic epidemiological risk assessments, assigned a tier to each of the 21 Italia...
Autores principales: | , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Authors. Published by Elsevier B.V.
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9212945/ https://www.ncbi.nlm.nih.gov/pubmed/35772295 http://dx.doi.org/10.1016/j.epidem.2022.100601 |
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author | Trentini, Filippo Manna, Adriana Balbo, Nicoletta Marziano, Valentina Guzzetta, Giorgio O’Dell, Samantha Kummer, Allisandra G. Litvinova, Maria Merler, Stefano Ajelli, Marco Poletti, Piero Melegaro, Alessia |
author_facet | Trentini, Filippo Manna, Adriana Balbo, Nicoletta Marziano, Valentina Guzzetta, Giorgio O’Dell, Samantha Kummer, Allisandra G. Litvinova, Maria Merler, Stefano Ajelli, Marco Poletti, Piero Melegaro, Alessia |
author_sort | Trentini, Filippo |
collection | PubMed |
description | BACKGROUND: After a rapid upsurge of COVID-19 cases in Italy during the fall of 2020, the government introduced a three-tiered restriction system aimed at increasing physical distancing. The Ministry of Health, after periodic epidemiological risk assessments, assigned a tier to each of the 21 Italian regions and autonomous provinces. It is still unclear to what extent these different sets of measures altered the number of daily interactions and the social mixing patterns. METHODS AND FINDINGS: We conducted a survey between July 2020 and March 2021 to monitor changes in social contact patterns among individuals in the metropolitan city of Milan, Italy, which was hardly hit by the second wave of the COVID-19 pandemic. The number of daily contacts during periods characterized by different levels of restrictions was analyzed through negative binomial regression models and age-specific contact matrices were estimated under the different tiers of restrictions. By relying on the empirically estimated mixing patterns, we quantified relative changes in SARS-CoV-2 transmission potential associated with the different tiers. As tighter restrictions were implemented during the fall of 2020, a progressive reduction in the mean number of daily contacts recorded by study participants was observed: from 15.9 % under mild restrictions (yellow tier), to 41.8 % under strong restrictions (red tier). Higher restrictions levels were also found to increase the relative contribution of contacts occurring within the household. The SARS-CoV-2 reproduction number was estimated to decrease by 17.1 % (95 %CI: 1.5–30.1), 25.1 % (95 %CI: 13.0–36.0) and 44.7 % (95 %CI: 33.9–53.0) under the yellow, orange, and red tiers, respectively. CONCLUSIONS: Our results give an important quantification of the expected contribution of different restriction levels in shaping social contacts and decreasing the transmission potential of SARS-CoV-2. These estimates can find an operational use in anticipating the effect that the implementation of these tiered restriction can have on SARS-CoV-2 reproduction number under an evolving epidemiological situation. |
format | Online Article Text |
id | pubmed-9212945 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | The Authors. Published by Elsevier B.V. |
record_format | MEDLINE/PubMed |
spelling | pubmed-92129452022-06-22 Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility Trentini, Filippo Manna, Adriana Balbo, Nicoletta Marziano, Valentina Guzzetta, Giorgio O’Dell, Samantha Kummer, Allisandra G. Litvinova, Maria Merler, Stefano Ajelli, Marco Poletti, Piero Melegaro, Alessia Epidemics Article BACKGROUND: After a rapid upsurge of COVID-19 cases in Italy during the fall of 2020, the government introduced a three-tiered restriction system aimed at increasing physical distancing. The Ministry of Health, after periodic epidemiological risk assessments, assigned a tier to each of the 21 Italian regions and autonomous provinces. It is still unclear to what extent these different sets of measures altered the number of daily interactions and the social mixing patterns. METHODS AND FINDINGS: We conducted a survey between July 2020 and March 2021 to monitor changes in social contact patterns among individuals in the metropolitan city of Milan, Italy, which was hardly hit by the second wave of the COVID-19 pandemic. The number of daily contacts during periods characterized by different levels of restrictions was analyzed through negative binomial regression models and age-specific contact matrices were estimated under the different tiers of restrictions. By relying on the empirically estimated mixing patterns, we quantified relative changes in SARS-CoV-2 transmission potential associated with the different tiers. As tighter restrictions were implemented during the fall of 2020, a progressive reduction in the mean number of daily contacts recorded by study participants was observed: from 15.9 % under mild restrictions (yellow tier), to 41.8 % under strong restrictions (red tier). Higher restrictions levels were also found to increase the relative contribution of contacts occurring within the household. The SARS-CoV-2 reproduction number was estimated to decrease by 17.1 % (95 %CI: 1.5–30.1), 25.1 % (95 %CI: 13.0–36.0) and 44.7 % (95 %CI: 33.9–53.0) under the yellow, orange, and red tiers, respectively. CONCLUSIONS: Our results give an important quantification of the expected contribution of different restriction levels in shaping social contacts and decreasing the transmission potential of SARS-CoV-2. These estimates can find an operational use in anticipating the effect that the implementation of these tiered restriction can have on SARS-CoV-2 reproduction number under an evolving epidemiological situation. The Authors. Published by Elsevier B.V. 2022-09 2022-06-17 /pmc/articles/PMC9212945/ /pubmed/35772295 http://dx.doi.org/10.1016/j.epidem.2022.100601 Text en © 2022 The Authors Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. |
spellingShingle | Article Trentini, Filippo Manna, Adriana Balbo, Nicoletta Marziano, Valentina Guzzetta, Giorgio O’Dell, Samantha Kummer, Allisandra G. Litvinova, Maria Merler, Stefano Ajelli, Marco Poletti, Piero Melegaro, Alessia Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility |
title | Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility |
title_full | Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility |
title_fullStr | Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility |
title_full_unstemmed | Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility |
title_short | Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility |
title_sort | investigating the relationship between interventions, contact patterns, and sars-cov-2 transmissibility |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9212945/ https://www.ncbi.nlm.nih.gov/pubmed/35772295 http://dx.doi.org/10.1016/j.epidem.2022.100601 |
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