Impact of mitigating interventions and temperature on the instantaneous reproduction number in the COVID-19 pandemic among 30 US metropolitan areas

Background: After more than six months into the coronavirus disease (COVID-19) pandemic, as of August 10, 2020, over 734,664 people had died worldwide. The current study aims to evaluate how mitigating interventions affected the epidemic process in the 30 largest metropolitan areas in the US and whe...

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Main Author: Xinhua Yu
Format: Article
Language:English
Published: Elsevier 2020-12-01
Series:One Health
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2352771420302615
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author Xinhua Yu
author_facet Xinhua Yu
author_sort Xinhua Yu
collection DOAJ
description Background: After more than six months into the coronavirus disease (COVID-19) pandemic, as of August 10, 2020, over 734,664 people had died worldwide. The current study aims to evaluate how mitigating interventions affected the epidemic process in the 30 largest metropolitan areas in the US and whether temperature played a role in the epidemic process. Methods: Publicly available data for the time series of COVID-19 cases and deaths and weather were analyzed at the metropolitan level. The time-varying reproductive numbers (Rt) based on retrospective moving average were used to explore the trends. Student t-tests were used to compare temperature and peak Rt cross-sectionally. Results: We found that virus transmissibility, measured by instantaneous reproduction number (Rt), had declined since the end of March for all areas and almost all of them reached a Rt of 1 or below after April 15, 2020. The timing of the main decline was concurrent with the implementation of mitigating interventions. However, the Rts remained around 1 for most areas since then and there were some small and short rebounds in some areas, suggesting a persistent epidemic in those areas when interventions were relaxed. Cities with warm temperature also tended to have a lower peak Rt than that of cities with cold temperature. However, they were not statistically significant and large geographic variations existed. Conclusions: Aggressive interventions might have mitigated the current pandemic of COVID-19, while temperature might have weak effects on the virus transmission. We may need to prepare for a possible return of the coronavirus outbreak.
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spelling doaj.art-95da3fe2bb3942c7ab8a7548b6c1a42c2022-12-21T23:10:05ZengElsevierOne Health2352-77142020-12-0110100160Impact of mitigating interventions and temperature on the instantaneous reproduction number in the COVID-19 pandemic among 30 US metropolitan areasXinhua Yu0Division of Epidemiology, Biostatistics and Environmental Health, School of Public Health, University of Memphis, USABackground: After more than six months into the coronavirus disease (COVID-19) pandemic, as of August 10, 2020, over 734,664 people had died worldwide. The current study aims to evaluate how mitigating interventions affected the epidemic process in the 30 largest metropolitan areas in the US and whether temperature played a role in the epidemic process. Methods: Publicly available data for the time series of COVID-19 cases and deaths and weather were analyzed at the metropolitan level. The time-varying reproductive numbers (Rt) based on retrospective moving average were used to explore the trends. Student t-tests were used to compare temperature and peak Rt cross-sectionally. Results: We found that virus transmissibility, measured by instantaneous reproduction number (Rt), had declined since the end of March for all areas and almost all of them reached a Rt of 1 or below after April 15, 2020. The timing of the main decline was concurrent with the implementation of mitigating interventions. However, the Rts remained around 1 for most areas since then and there were some small and short rebounds in some areas, suggesting a persistent epidemic in those areas when interventions were relaxed. Cities with warm temperature also tended to have a lower peak Rt than that of cities with cold temperature. However, they were not statistically significant and large geographic variations existed. Conclusions: Aggressive interventions might have mitigated the current pandemic of COVID-19, while temperature might have weak effects on the virus transmission. We may need to prepare for a possible return of the coronavirus outbreak.http://www.sciencedirect.com/science/article/pii/S2352771420302615Virus transmissibilityReproduction numberMitigating interventionTemperatureCOVID-19 epidemic
spellingShingle Xinhua Yu
Impact of mitigating interventions and temperature on the instantaneous reproduction number in the COVID-19 pandemic among 30 US metropolitan areas
One Health
Virus transmissibility
Reproduction number
Mitigating intervention
Temperature
COVID-19 epidemic
title Impact of mitigating interventions and temperature on the instantaneous reproduction number in the COVID-19 pandemic among 30 US metropolitan areas
title_full Impact of mitigating interventions and temperature on the instantaneous reproduction number in the COVID-19 pandemic among 30 US metropolitan areas
title_fullStr Impact of mitigating interventions and temperature on the instantaneous reproduction number in the COVID-19 pandemic among 30 US metropolitan areas
title_full_unstemmed Impact of mitigating interventions and temperature on the instantaneous reproduction number in the COVID-19 pandemic among 30 US metropolitan areas
title_short Impact of mitigating interventions and temperature on the instantaneous reproduction number in the COVID-19 pandemic among 30 US metropolitan areas
title_sort impact of mitigating interventions and temperature on the instantaneous reproduction number in the covid 19 pandemic among 30 us metropolitan areas
topic Virus transmissibility
Reproduction number
Mitigating intervention
Temperature
COVID-19 epidemic
url http://www.sciencedirect.com/science/article/pii/S2352771420302615
work_keys_str_mv AT xinhuayu impactofmitigatinginterventionsandtemperatureontheinstantaneousreproductionnumberinthecovid19pandemicamong30usmetropolitanareas