Mass General study shows physical distancing slowed growth of COVID-19 in US

August 11, 2020

BOSTON - Between March 10 and March 25, 2020, all 50 states and the District of Columbia enacted at least one statewide physical distancing measure to help stop the spread of COVID-19. New research from clinicians at Massachusetts General Hospital (MGH) show these government-issued physical distancing orders significantly slowed the COVID-19 epidemic, leading to an estimated reduction of more than 600,000 cases within three weeks of implementation. The findings were recently published in PLOS Medicine.

"Many have strongly suspected that physical distancing policies helped interrupt COVID-19 transmission during the early days of the U.S. epidemic," said Mark J. Siedner, MD, MPH, an infectious diseases physician at MGH and Associate Professor of Medicine at Harvard Medical School, who co-authored the research. "This study adds clear evidence to support those suspicions. The results show the timing of government-issued orders correlated strongly with reductions in both cases and deaths. In short, these measures work, and policy makers should use them as an arrow in their quivers to get on top of local epidemics where they are not responding to containment measures."

The MGH researchers - in collaboration with colleagues at University College London, the Harvard T.H. Chan School of Public Health, and the Perelman School of Medicine at the University of Pennsylvania - analyzed data from the first five months of the COVID-19 epidemic in the U.S. They collected data on government-issued orders on statewide physical distancing measures and compared changes in COVID-19 cases and COVID-19-attributed deaths in states that implemented physical distancing measures before and after implementation.

The results show the average daily COVID-19 case growth rate began declining approximately one incubation period (i.e. four days) after implementation of the first statewide physical distancing measures. The period of time required for the number of cases to double (epidemic doubling time) increased from approximately four days to eight days within three weeks of implementation. These findings are consistent with other recently published work. What is unique to this new study is researchers found that the average daily COVID-19-attributed death rate also began declining after the implementation of physical distancing measures, which prior to this study had not been analyzed.

The study looked at a wide array of measures, including school and business closures, restrictions on public gathering, and shelter-in-place orders. Most combinations of these orders appeared to have similarly beneficial effects. Because the different types of physical distancing measures were generally implemented in close temporal proximity to each other, the research team was unable to determine specifically which types of physical distancing measures were most effective.

The findings of the model suggest that statewide physical distancing measures reduced the total number of reported COVID-19 cases by approximately 1,600 cases by one week after implementation and - due to the exponential growth of the spread - by approximately 621,000 cases by three weeks after implementation.

One of the most significant limitations of the study is that the implementation of statewide physical distancing measures was not a controlled experiment. If state governments intensified physical distancing measures in response to worsening local epidemics, the analysis would likely have shown that the policies were less effective. The authors further emphasize that, in many states, people may have begun spontaneously changing their behavior in response to a worsening local epidemic even prior to any statewide measures.

"The findings show that physical distancing measures slowed the growth of the COVID-19 epidemic and saved lives, and also bought our health care leaders some time to fortify their surge capacity to deal with the epidemic," said senior author Alexander C. Tsai, MD, psychiatrist at MGH and Associate Professor of Psychiatry at Harvard Medical School. "Unfortunately, the national response has largely abdicated the responsibilities of planning a coordinated response, so we probably could have done more sooner. This means much of the time before these local measures were implemented was simply wasted."

Added Siedner: "This is a case where past success does not predict future control. COVID-19 case growth appears to be trending upward in many states around the country, including Massachusetts. If containment and more conservative measures fail, we should be prepared to slow or reverse reopening efforts. Until a vaccine is made available and widely deployed in an equitable fashion, we have few other options. Fortunately, our data show that these measures work -- if we have the wherewithal to use them."
-end-
The research study was supported in part by grants from the Wellcome Trust and the Sullivan Family Foundation.

About the Massachusetts General Hospital

Massachusetts General Hospital, founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH Research Institute conducts the largest hospital-based research program in the nation, with an annual research budget of more than $1 billion and comprises more than 8,500 researchers working across more than 30 institutes, centers and departments. In August 2020 the MGH was named #6 in the nation by U.S. News & World Report in its list of "America's Best Hospitals."

Massachusetts General Hospital

Related Public Health Articles from Brightsurf:

COVID-19 and the decolonization of Indigenous public health
Indigenous self-determination, leadership and knowledge have helped protect Indigenous communities in Canada during the coronavirus disease 2019 (COVID-19) pandemic, and these principles should be incorporated into public health in future, argue the authors of a commentary in CMAJ (Canadian Medical Association Journal) http://www.cmaj.ca/lookup/doi/10.1503/cmaj.200852.

Public health consequences of policing homelessness
In a new study examining homelessness, researchers find that policy such a lifestyle has massive public health implications, making sleeping on the street even MORE unhealthy.

Electronic health information exchange improves public health disease reporting
Disease tracking is an important area of focus for health departments in the midst of the COVID-19 pandemic.

Pandemic likely to cause long-term health problems, Yale School of Public Health finds
The coronavirus pandemic's life-altering effects are likely to result in lasting physical and mental health consequences for many people--particularly those from vulnerable populations--a new study led by the Yale School of Public Health finds.

The Lancet Public Health: US modelling study estimates impact of school closures for COVID-19 on US health-care workforce and associated mortality
US policymakers considering physical distancing measures to slow the spread of COVID-19 face a difficult trade-off between closing schools to reduce transmission and new cases, and potential health-care worker absenteeism due to additional childcare needs that could ultimately increase mortality from COVID-19, according to new modelling research published in The Lancet Public Health journal.

The Lancet Public Health: Access to identification documents reflecting gender identity may improve trans mental health
Results from a survey of over 20,000 American trans adults suggest that having access to identification documents which reflect their identified gender helps to improve their mental health and may reduce suicidal thoughts, according to a study published in The Lancet Public Health journal.

The Lancet Public Health: Study estimates mental health impact of welfare reform, Universal Credit, in Great Britain
The 2013 Universal Credit welfare reform appears to have led to an increase in the prevalence of psychological distress among unemployed recipients, according to a nationally representative study following more than 52,000 working-age individuals from England, Wales, and Scotland over nine years between 2009-2018, published as part of an issue of The Lancet Public Health journal on income and health.

BU researchers: Pornography is not a 'public health crisis'
Researchers from the Boston University School of Public Health (BUSPH) have written an editorial in the American Journal of Public Health special February issue arguing against the claim that pornography is a public health crisis, and explaining why such a claim actually endangers the health of the public.

The Lancet Public Health: Ageism linked to poorer health in older people in England
Ageism may be linked with poorer health in older people in England, according to an observational study of over 7,500 people aged over 50 published in The Lancet Public Health journal.

Study: Public transportation use linked to better public health
Promoting robust public transportation systems may come with a bonus for public health -- lower obesity rates.

Read More: Public Health News and Public Health Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.