The effect of large-scale anti-contagion policies on the COVID-19 pandemic
Solomon Hsiang, Daniel Allen, Sébastien Annan-Phan, Kendon Bell, Ian Bolliger, Trinetta Chong, Hannah Druckenmiller, Luna Yue Huang, Andrew Hultgren, Emma Krasovich, Peiley Lau, Jaecheol Lee, Esther Rolf, Jeanette Tseng & Tiffany Wu
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Received: 22 March 2020
Accepted: 26 May 2020
Accelerated Article Preview Published
online 8 June 2020
Cite this article as: Hsiang, S. et al. The effect of large-scale anti-contagion policies on the COVID-19 pandemic. Nature https://doi. org/10.1038/s41586-020-2404-8 (2020).
Governments around the world are responding to the novel coronavirus (COVID-19) pandemic1 with unprecedented policies designed to slow the growth rate of infections. Many actions, such as closing schools and restricting populations to their homes, impose large and visible costs on society, but their benefts cannot be directly observed and are currently understood only through process-based simulations2–4 . Here, we compile new data on 1,717 local, regional, and national non-pharmaceutical interventions deployed in the ongoing pandemic across localities in China, South Korea, Italy, Iran, France, and the United States (US). We then apply reduced-form econometric methods, commonly used to measure the efect of policies on economic growth5,6 , to empirically evaluate the efect that these anti-contagion policies have had on the growth rate of infections. In the absence of policy actions, we estimate that early infections of COVID-19 exhibit exponential growth rates of roughly 38% per day. We fnd that anti-contagion policies have signifcantly and substantially slowed this growth. Some policies have diferent impacts on diferent populations, but we obtain consistent evidence that the policy packages now deployed are achieving large, benefcial, and measurable health outcomes. We estimate that across these six countries, interventions prevented or delayed on the order of 62 million confrmed cases, corresponding to averting roughly 530 million total infections. These fndings may help inform whether or when these policies should be deployed, intensifed, or lifted, and they can support decision-making in the other 180+ countries where COVID-19 has been reported7 .
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Our results suggest that ongoing anti-contagion policies have already substantially reduced the number of COVID-19 infections observed in the world today (Figure 4). Our central estimates suggest that there would be roughly 37 million more cumulative confirmed cases (corresponding to 285 million more total infections, including the confirmed cases) in China, 11.5 million more confirmed cases in South Korea (38 million total infections), 2.1 million more confirmed cases in Italy (49 million total infections), 5 million more confirmed cases in Iran (54 million total infections), 1.4 million more confirmed cases in France (45 million total infections),
and 4.8 million more confirmed cases (60 million total infections) in the US
had these countries never enacted any anti-contagion policies since the start of the pandemic.
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Discussion Our empirical results indicate that large-scale anti-contagion policies are slowing the COVID-19 pandemic. Because infection rates in the countries we study would have initially followed rapid exponential growth had no policies been applied, our results suggest that these policies have provided large health benefits. For example, we estimate that there would be roughly 465 × the observed number of confirmed cases in China, 17 × in Italy, and 14 × in the US by the end of our sample if large-scale anti-contagion policies had not been deployed. Consistent with process-based simulations of COVID-19 infections2,4,8,9,22,26, our analysis of existing policies indicates that seemingly small delays in policy deployment likely produced dramatically different health outcomes...
snip...see full text;
Our results suggest that ongoing anti-contagion policies have already substantially reduced the number of COVID-19 infections observed in the world today (Figure 4). Our central estimates suggest that there would be roughly 37 million more cumulative confirmed cases (corresponding to 285 million more total infections, including the confirmed cases) in China, 11.5 million more confirmed cases in South Korea (38 million total infections), 2.1 million more confirmed cases in Italy (49 million total infections), 5 million more confirmed cases in Iran (54 million total infections), 1.4 million more confirmed cases in France (45 million total infections),
and 4.8 million more confirmed cases (60 million total infections) in the US
had these countries never enacted any anti-contagion policies since the start of the pandemic.
Texas Covid-19 Nursing Homes and Assisted Living Facilities
COVID-19 in Nursing Homes
Public Health Region Number of Nursing Homes with Confirmed Resident or Staff Cases of COVID-19 Number of Confirmed Cases among Nursing Home Residents Number of Fatalities among Nursing Home Residents Number of Reported Recoveries among Nursing Home Residents
1 36 323 67 153
2/3 157 1405 224 607
4/5N 56 521 91 175
6/5S 120 1070 160 347
7 49 514 106 185
8 45 255 29 81
9/10 23 235 43 97
11 20 161 37 94
Total 506 4484 757 1739
COVID-19 in Assisted Living Facilities
Public Health Region Number of Assisted Living Facilities with Confirmed Resident or Staff Cases of COVID-19 Number of Confirmed Cases among Assisted Living Facility Residents Number of Fatalities among Assisted Living Facility Residents Number of Reported Recoveries among Assisted Living Facility Residents
1 11 38 2 8
2/3 48 198 57 74
4/5N 7 17 5 11
6/5S 59 178 34 110
7 15 98 17 34
8 3 7 4 2
9/10 3 3 0 2
11 2 6 2 1
Total 148 545 121 242
Galveston County Death rate rising
Galveston County Case Rate rising
Texas reported a record-breaking number of COVID-19 hospitalizations Monday as the governor plans to reopen more businesses and double capacity.
Texas Department of State Health Services figures show 1,935 people were admitted as hospital patients for coronavirus-related treatment. That is up from a previous record of 1,888 on May 5.
The department's new figures were released as Gov. Greg Abbott moves forward with a plan to open bars, restaurants, amusement parks and other businesses to 50% capacity.
Abbott led most of the nation's governors in allowing Texas to lift statewide stay-at-home orders and urging businesses to reopen at limited capacity on May 1.
But even in states where officials left stringent restrictions in place, the number of newly diagnosed cases are rising. About 20 states, including California and Arizona, have also reported a rise in COVID-19 cases in recent weeks, according to The New York Times. Meanwhile, state leaders have come under increasing pressure to restart the economy.
NEWS RELEASE 9-JUN-2020
Widespread facemask use could shrink the 'R' number and prevent a second COVID-19 wave
UNIVERSITY OF CAMBRIDGE
Population-wide use of facemasks keeps the coronavirus 'reproduction number' under 1.0, and prevents further waves of the virus when combined with lockdowns, a modelling study from the universities of Cambridge and Greenwich suggests.
The research suggests that lockdowns alone will not stop the resurgence of SARS-CoV-2, and that even homemade masks with limited effectiveness can dramatically reduce transmission rates if worn by enough people, regardless of whether they show symptoms.
The researchers call for information campaigns across wealthy and developing nations alike that appeal to our altruistic side: "my facemask protects you, your facemask protects me". The findings are published in the Proceedings of the Royal Society A.
"Our analyses support the immediate and universal adoption of facemasks by the public," said lead author, Dr Richard Stutt, part of a team that usually models the spread of crop diseases at Cambridge's Department of Plant Sciences.
"If widespread facemask use by the public is combined with physical distancing and some lockdown, it may offer an acceptable way of managing the pandemic and re-opening economic activity long before there is a working vaccine."
Dr Renata Retkute, coauthor and Cambridge team member, said: "The UK government can help by issuing clear instructions on how to make and safely use homemade masks."
"We have little to lose from the widespread adoption of facemasks, but the gains could be significant."
The new coronavirus is transmitted through airborne droplets loaded with SARS-CoV-2 particles that get exhaled by infectious people, particularly when talking, coughing or sneezing.
For the latest study, Cambridge researchers worked to link the dynamics of spread between individuals with population-level models, to assess different scenarios of facemask adoption combined with periods of lockdown.
The modelling included stages of infection and transmission via surfaces as well as air. Researchers also considered negative aspects of mask use, such as increased face touching.
The reproduction or 'R' number - the number of people an infected individual passes the virus onto - needs to stay below 1.0 for the pandemic to slow.
The study found that if people wear masks whenever they are in public it is twice as effective at reducing 'R' than if masks are only worn after symptoms appear.
In all modelling scenarios, routine facemask use by 50% or more of the population reduced COVID-19 spread to an R less than 1.0, flattening future disease waves and allowing less-stringent lockdowns.
Viral spread reduced further as more people adopted masks when in public. 100% mask adoption combined with on/off lockdowns prevented any further disease resurgence for the 18 months required for a possible vaccine.
The models suggest that - while the sooner the better - a policy of total facemask adoption can still prevent a second wave even if it isn't instigated until 120 days after an epidemic begins (defined as the first 100 cases).
The team investigated the varying effectiveness of facemasks. Previous research shows that even homemade masks made from cotton t-shirts or dishcloths can prove 90% effective at preventing transmission.
The study suggests that an entire population wearing masks of just 75% effectiveness can bring a very high 'R' number of 4.0 - the UK was close to this before lockdown - all the way down to under 1.0, even without aid of lockdowns.
In fact, masks that only capture a mere 50% of exhaled droplets would still provide a "population-level benefit", even if they quadrupled the wearer's own contamination risk through frequent face touching and mask adjustment (a highly unlikely scenario).
The researchers point out that crude homemade masks primarily reduce disease spread by catching the wearer's own virus particles, breathed directly into fabric, whereas inhaled air is often sucked in around the exposed sides of the mask.
"There is a common perception that wearing a facemask means you consider others a danger," said Professor John Colvin, coauthor from the University of Greenwich. "In fact, by wearing a mask you are primarily protecting others from yourself."
"Cultural and even political issues may stop people wearing facemasks, so the message needs to be clear: my mask protects you, your mask protects me."
"In the UK, the approach to facemasks should go further than just public transport. The most effective way to restart daily life is to encourage everyone to wear some kind of mask whenever they are in public," Colvin said.
Prof Chris Gilligan, coauthor from Cambridge's Epidemiology and Modelling Group in the Department of Plant Sciences, added: "These messages will be vital if the disease takes hold in the developing world, where large numbers of people are resource poor, but homemade masks are a cheap and effective technology."
###
Research articles
A modelling framework to assess the likely effectiveness of facemasks in combination with ‘lock-down’ in managing the COVID-19 pandemic
Richard O. J. H. Stutt, Renata Retkute, Michael Bradley, Christopher A. Gilligan and John Colvin
Published:10 June 2020https://doi.org/10.1098/rspa.2020.0376
Review history
Abstract
COVID-19 is characterized by an infectious pre-symptomatic period, when newly infected individuals can unwittingly infect others. We are interested in what benefits facemasks could offer as a non-pharmaceutical intervention, especially in the settings where high-technology interventions, such as contact tracing using mobile apps or rapid case detection via molecular tests, are not sustainable. Here, we report the results of two mathematical models and show that facemask use by the public could make a major contribution to reducing the impact of the COVID-19 pandemic. Our intention is to provide a simple modelling framework to examine the dynamics of COVID-19 epidemics when facemasks are worn by the public, with or without imposed ‘lock-down’ periods. Our results are illustrated for a number of plausible values for parameter ranges describing epidemiological processes and mechanistic properties of facemasks, in the absence of current measurements for these values. We show that, when facemasks are used by the public all the time (not just from when symptoms first appear), the effective reproduction number, Re, can be decreased below 1, leading to the mitigation of epidemic spread. Under certain conditions, when lock-down periods are implemented in combination with 100% facemask use, there is vastly less disease spread, secondary and tertiary waves are flattened and the epidemic is brought under control. The effect occurs even when it is assumed that facemasks are only 50% effective at capturing exhaled virus inoculum with an equal or lower efficiency on inhalation. Facemask use by the public has been suggested to be ineffective because wearers may touch their faces more often, thus increasing the probability of contracting COVID-19. For completeness, our models show that facemask adoption provides population-level benefits, even in circumstances where wearers are placed at increased risk. At the time of writing, facemask use by the public has not been recommended in many countries, but a recommendation for wearing face-coverings has just been announced for Scotland. Even if facemask use began after the start of the first lock-down period, our results show that benefits could still accrue by reducing the risk of the occurrence of further COVID-19 waves. We examine the effects of different rates of facemask adoption without lock-down periods and show that, even at lower levels of adoption, benefits accrue to the facemask wearers. These analyses may explain why some countries, where adoption of facemask use by the public is around 100%, have experienced significantly lower rates of COVID-19 spread and associated deaths. We conclude that facemask use by the public, when used in combination with physical distancing or periods of lock-down, may provide an acceptable way of managing the COVID-19 pandemic and re-opening economic activity. These results are relevant to the developed as well as the developing world, where large numbers of people are resource poor, but fabrication of home-made, effective facemasks is possible. A key message from our analyses to aid the widespread adoption of facemasks would be: ‘my mask protects you, your mask protects me’.
snip...
In summary, our modelling analyses provide support for the immediate, universal adoption of facemasks by the public, similar to what has been done in Taiwan, for example, where production will soon reach 13 million facemasks daily, with well-developed plans for N95 respirator production in the pipeline [68]. Our analyses indicate that actions to facilitate this in the UK should include clear instructions on the fabrication and safe use of home-made masks, as well as accompanying governmental policies to increase swiftly the availability of medical standard surgical, or N95 respirators, to the public.
Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2)
View ORCID ProfileRuiyun Li1,*, View ORCID ProfileSen Pei2,*,†, View ORCID ProfileBin Chen3,*, View ORCID ProfileYimeng Song4, Tao Zhang5, View ORCID ProfileWan Yang6, View ORCID ProfileJeffrey Shaman2,† See all authors and affiliations
Science 01 May 2020: Vol. 368, Issue 6490, pp. 489-493 DOI: 10.1126/science.abb3221
Undetected cases The virus causing coronavirus disease 2019 (COVID-19) has now become pandemic. How has it managed to spread from China to all around the world within 3 to 4 months? Li et al. used multiple sources to infer the proportion of early infections that went undetected and their contribution to virus spread. The researchers combined data from Tencent, one of the world's largest social media and technology companies, with a networked dynamic metapopulation model and Bayesian inference to analyze early spread within China. They estimate that ∼86% of cases were undocumented before travel restrictions were put in place. Before travel restriction and personal isolation were implemented, the transmission rate of undocumented infections was a little more than half that of the known cases. However, because of their greater numbers, undocumented infections were the source for ∼80% of the documented cases. Immediately after travel restrictions were imposed, ∼65% of cases were documented. These findings help to explain the lightning-fast spread of this virus around the world.
Science, this issue p. 489
Abstract Estimation of the prevalence and contagiousness of undocumented novel coronavirus [severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2)] infections is critical for understanding the overall prevalence and pandemic potential of this disease. Here, we use observations of reported infection within China, in conjunction with mobility data, a networked dynamic metapopulation model, and Bayesian inference, to infer critical epidemiological characteristics associated with SARS-CoV-2, including the fraction of undocumented infections and their contagiousness. We estimate that 86% of all infections were undocumented [95% credible interval (CI): 82–90%] before the 23 January 2020 travel restrictions. The transmission rate of undocumented infections per person was 55% the transmission rate of documented infections (95% CI: 46–62%), yet, because of their greater numbers, undocumented infections were the source of 79% of the documented cases. These findings explain the rapid geographic spread of SARS-CoV-2 and indicate that containment of this virus will be particularly challenging.
Reducing transmission of SARS-CoV-2
Kimberly A. Prather1, Chia C. Wang,2,3 Robert T. Schooley4
1Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92037, USA. 2Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan 804, Republic of China. 3Aerosol Science Research Center, National Sun Yat-Sen University, Kaohsiung, Taiwan 804, Republic of China. 4Department of Medicine, Division of Infectious Diseases and Global Public Health, School of Medicine, University of California San Diego, La Jolla, CA 92093, USA. Email: kprather@ucsd.edu
Masks and testing are necessary to combat asymptomatic spread in aerosols and droplets
Respiratory infections occur through the transmission of virus-containing droplets (>5 to 10 μm) and aerosols (≤5 μm) exhaled from infected individuals during breathing, speaking, coughing, and sneezing. Traditional respiratory disease control measures are designed to reduce transmis- sion by droplets produced in the sneezes and coughs of in- fected individuals. However, a large proportion of the spread of coronavirus disease 2019 (COVID-19) appears to be occurring through airborne transmission of aerosols pro- duced by asymptomatic individuals during breathing and speaking (1–3). Aerosols can accumulate, remain infectious in indoor air for hours, and be easily inhaled deep into the lungs. For society to resume, measures designed to reduce aerosol transmission must be implemented, including uni- versal masking and regular, widespread testing to identify and isolate infected asymptomatic individuals.
Snip...
Aerosol transmission of viruses must be acknowledged as a key factor leading to the spread of infectious respiratory diseases. Evidence suggests that SARS-CoV-2 is silently spreading in aerosols exhaled by highly contagious infected individuals with no symptoms. Owing to their smaller size, aerosols may lead to higher severity of COVID-19 because virus-containing aerosols penetrate more deeply into the lungs (10). It is essential that control measures be intro- duced to reduce aerosol transmission. A multidisciplinary approach is needed to address a wide range of factors that lead to the production and airborne transmission of respira- tory viruses, including the minimum virus titer required to cause COVID-19; viral load emitted as a function of droplet size before, during, and after infection; viability of the virus indoors and outdoors; mechanisms of transmission; air- borne concentrations; and spatial patterns. More studies of the filtering efficiency of different types of masks are also needed. COVID-19 has inspired research that is already lead- ing to a better understanding of the importance of airborne transmission of respiratory disease.
SUNDAY, MAY 17, 2020
CORONAVIRUS IN TEXAS, More than 700 new cases of coronavirus meatpacking plants Amarillo region, 11 county deaths connected to Long Term Care Facility at Texas City
CORONAVIRUS IN TEXAS
SATURDAY, MAY 9, 2020
Covid-19 Mortality, Crunching the Numbers, Children, The Jungle 1906 to 2020
TUESDAY, JUNE 2, 2020
USDA APHIS Confirmation of COVID-19 in Pet Dog in New York
WEDNESDAY, APRIL 22, 2020
APHIS Confirmation of COVID-19 in Two Pet Cats in New York
Terry S. Singeltary Sr.
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