Social distancing and COVID-19: A law of diminishing returns
Research finds distancing helps ease the burden on hospitals -- but only to a point
July 15, 2020
Science Daily/Washington University in St. Louis
The first case of the novel coronavirus, COVID-19, in the United States was in late January. By mid-March, "social distancing" had entered the public lexicon. People altered their routines and local jurisdictions suggested, urged, or required changes meant to slow the disease's spread.
By the end of June, however, public health officials and news outlets were talking about a second wave. In July, many states were pausing or reversing their plans to reopen while, for the second time, hospital systems worried about running out of room.
What could we have done better?
In an "editor's pick" paper published today in the journal Chaos of the American Institute of Physics, Washington University in St. Louis researchers in the lab of Rajan Chakrabarty, associate professor in the department of Energy, Environmental and Chemical Engineering at the McKelvey School of Engineering, modeled the interplay between the duration and intensity of social distancing. They found a law of diminishing returns, showing that longer periods of social distancing are not always more successful when it comes to slowing the spread, and that any strategy that involves social distancing requires other steps be taken in tandem.
"Conventional wisdom was, the more intense and long-term the social distancing, the more you will curb the disease spread," Chakrabarty said
"But that is true if you have social distancing implemented with contact tracing, isolation and testing. Without those, you will give rise to a second wave."
Added Payton Beeler, a second year doctoral student in Chakrabarty's lab, who also worked with Pai Liu, a postdoctoral fellow: "What we have found is that if social distancing is the only measure taken, it must be implemented extremely carefully in order for its benefits to be fully realized."
Their susceptible, exposed, infected, and recovered (SEIR) dynamics model used data gathered by Johns Hopkins University between March 18 and March 29, a period marked by a rapid surge in COVID-19 cases and the onset of social distancing in most US states. Calibrating their model using these datasets allowed the authors to analyze unbiased results that had not yet been affected by large-scale distancing in place.
Unique to this project was the use of age stratification; the model included details on how much people of different age groups interact, and how that affects the spread of transmission.
No matter what strategy they looked at, one thing was clear, Chakrabarty said: "Had social distancing been implemented earlier, we probably would've done a better job."
Researchers found that, over the short-term, more distancing and less hospital demand go hand in hand -- but only up to two weeks. After that, time spent distancing does not benefit hospital demand as much; society would have to increase social distancing time exponentially in order to see a linear decrease in hospital demand.
Thus the diminishing return: Society would see smaller and smaller benefits to hospital demand the longer it spent social distancing.
If social distancing "alone" is to be implemented longer than two weeks, a moderate shut down, say between 50-70%, could be more effective for the society than a stricter complete shut-down in yielding the largest reduction in medical demands.
Another strategy for flattening the curve involves acting intermittently, alternating between strict social distancing and no distancing to alleviate the strain on hospitals -- as well as some of the other strains on the economy and well-being imposed by longer-term distancing.
According to the model, the most efficient distancing- to- no-distancing ratio is 5 to 1; one day of no distancing for every five days at home. Had society acted in this way, hospital burden could have been reduced by 80%, Chakrabarty said. Exceeding this ratio, the model showed a diminishing return.
Critically, the researchers note that social distancing policy as a whole-of-government approach could not be successful without the implementation of wide-spread testing, contact tracing, and isolation of those found to be infected.
"And you have to do it aggressively," Chakrabarty said. "If you do not, what you're going to do, the moment you lift social distancing, is give rise to a second wave."
That's because the people who are leaving their homes after distancing themselves are, ostensibly, all susceptible to COVID-19.
"Bending the curve using social distancing alone is analogous to slowing down the front of a raging wildfire without extinguishing the glowing embers," said Chakrabarty, whose other line of research focuses on the impacts of wildfires on climate and health.
"They are waiting to start their own fires once the wind carries them away."
The model cannot inform strategies going forward because it used data collected in March, before any large-scale social distancing was implemented. But Chakrabarty said it may be able to inform our actions if we find ourselves in a similar situation in the future.
"Next time, we must act faster, and be more aggressive when it comes to contact tracing and testing and isolation," Chakrabarty said. "Or else this work was for nothing."
https://www.sciencedaily.com/releases/2020/07/200715160005.htm
Individuals physically distanced before state mandates, slowing COVID-19 spread
July 2, 2020
Science Daily/Johns Hopkins University
Residents in all 25 of the U.S. counties hardest hit by COVID-19 began to limit their public movements six to 29 days before states implemented stay-at-home orders, according to Johns Hopkins University researchers.
The decline in the number of daily trips people made as tracked by mobile phone data helped slow the spread of the virus, according to findings published today in The Lancet Infectious Diseases journal from the Johns Hopkins team that created the world-famous online coronavirus tracking map.
"Our results strongly support the conclusion that social distancing played a crucial role in the reduction of case growth rates in multiple U.S. counties during March and April, and is therefore an effective mitigation policy for COVID-19 in the United States," said Lauren Gardner, co-director of the Center for Systems Science and Engineering at Johns Hopkins, who led the research team.
"Critically, if individual-level actions were not taken and social distancing behavior was delayed until the state-level directives were implemented, COVID-19 would have been able to circulate unmitigated for additional weeks in some locations, inevitably resulting in more infections and deaths," Gardner added. "This demonstrates that it is within the power of each U.S. resident to help slow the spread of COVID-19."
Despite some county-level restrictions being implemented earlier than state policies, 21 out of the 25 counties recorded initial declines in movement before even those local steps.
Determining the effectiveness of social distancing is difficult because counties and states implemented different policies at different times. To establish a reliable indicator of social distancing the researchers used real-world mobile phone movement data.
Their first step was to establish a baseline of normal movement between Jan. 8-31. They then examined changes through April 16 in the 25 U.S. counties with the highest numbers of confirmed COVID-19 cases.
From Jan. 24 to April 17, people made far fewer daily trips than they did during the baseline period. Individuals began to reduce movement in early March, indicating that social distancing began well before the first state, California, imposed a stay-at-home directive on March 21.
In New York City, for example, residents had limited movement to 35% of the baseline, the most-significant reduction in movement among the 25 jurisdictions.
Harris County, Texas, which includes Houston, displayed the least change. Its residents slowed their normal movements but only to 65% of the movements measured in January. Data for all 25 counties are detailed in the research.
Social distancing will remain one of the most important ways to control the spread of infections until a vaccine is available.
"Individuals seem to have anticipated public health directives in March and April, despite a mixed political message," Hamada Badr, a co-author and research scientist in the Department of Earth and Planetary Sciences at Johns Hopkins. "As stay-at-home policies began to relax, we urge individuals and governments to make safe and data-driven decisions, to respond to the potential risk of increased infections. More timely, consistent and decisive policy implementation of social distancing and other known effective mitigation measures is urgently needed."
https://www.sciencedaily.com/releases/2020/07/200702100547.htm
Coronavirus: Social distancing accepted when people understand exponential growth
June 29, 2020
Science Daily/University of Cologne
Experiments among U.S. population show: When people fail to see the need for restrictions on public life, explaining the exponential increase of infections creates greater acceptance for measures taken to slow down the infection rate.
Researchers from the Social Cognition Center Cologne at the University of Cologne and from the University of Bremen report that participants in three experiments, each involving more than 500 adults in the United States, tended to assume the number of COVID-19 cases grew linearly with time, rather than exponentially. As a result, they underestimated actual virus growth. Interventions designed to help people avoid this bias led to an improved understanding of virus growth and increased support for social distancing measures compared with participants who did not receive such instructions.
The experiments were conducted by the social psychologist Dr Joris Lammers of the Social Cognition Center Cologne and the University of Bremen and his co-authors, the social psychologists Jan Crusius and Anne Gast, also from the University of Cologne. The article "Correcting misperceptions of exponential coronavirus growth increases support for social distancing" has been published in the current issue of Proceedings of the National Academy of Sciences.
The most effective way to stem the spread of a pandemic such as COVID-19 is what has come to be known as 'social distancing'. But the introduction of such measures is hampered by the fact that a sizeable part of the population fails to see their need. Many social scientists see the root of this perception in what they call the exponential growth bias. "In general, people have difficulty understanding exponential growth and erroneously interpret it in linear terms instead," explains first author Joris Lammers. The result is a gross underestimation of the growth of the infection rate and a misunderstanding of the potential to slow it down through social distancing. "Our current work tests the role of exponential growth bias in shaping the public's view on social distancing to contain the coronavirus's spreading."
Three studies were conducted during the mass spreading of the virus in the United States toward the end of March 2020. The first study focused on participants' understandings of linear growth, showing that many Americans mistakenly perceive the virus's exponential growth in linear terms. Interestingly, political orientation also played a role: conservatives were more prone to this misunderstanding than liberals. Studies 2 and 3 showed that instructing people to avoid the exponential growth bias significantly increases correct perceptions of the virus's growth and thereby support for social distancing. "Together, these results show the importance of statistical literacy to recruit support for fighting pandemics such as the coronavirus," said Lammers.
"Our results stand in contrast to earlier literature showing that the exponential growth bias is difficult to overcome," he explained. "The reason for this is that the current study focuses on a threat with great personal relevance and media presence, which likely increases subjective availability and thus the estimated probability of the risk."
Given that social distancing is the most effective way to combat the coronavirus currently available, these findings can have a significant impact: They show that bias, among other things, influences political opinions about matters of life and death, Lammers believes. Most important for team is to show the necessity of statistical literacy and to improve that skill among the general public.
https://www.sciencedaily.com/releases/2020/06/200629120142.htm
Survey finds large increase in psychological distress reported among US adults during the COVID-19 pandemic
June 3, 2020
Science Daily/Johns Hopkins University Bloomberg School of Public Health
A new survey conducted by researchers at the Johns Hopkins Bloomberg School of Public Health during the COVID-19 pandemic found a more-than-threefold increase in the percentage of U.S. adults who reported symptoms of psychological distress -- from 3.9 percent in 2018 to 13.6 percent in April 2020. The percentage of adults ages 18-29 in the U.S. who reported psychological distress increased from 3.7 percent in 2018 to 24 percent in 2020.
The survey, fielded online April 7 to April 13, found that 19.3 percent of adults with annual household incomes less than $35,000 reported psychological distress in 2020 compared to 7.9 percent in 2018, an increase of 11.4 percentage points. Nearly one-fifth, or 18.3 percent, of Hispanic adults reported psychological distress in 2020 compared to 4.4 percent in 2018, a more than four-fold increase of 13.9 percentage points. The researchers also found that psychological distress in adults age 55 and older almost doubled from 3.8 percent in 2018 to 7.3 percent in 2020.
The survey found only a slight increase in feelings of loneliness, from 11 percent in 2018 to 13.8 percent in 2020, suggesting that loneliness is not driving increased psychological distress.
The findings were published online June 3 in a research letter in JAMA.
The disruptions of the COVID-19 pandemic -- social distancing, fear of contracting the disease, economic uncertainty, including high unemployment -- have negatively affected mental health. The pandemic has also disrupted access to mental health services.
"We need to prepare for higher rates of mental illness among U.S .adults post-COVID," says McGinty. "It is especially important to identify mental illness treatment needs and connect people to services, with a focus on groups with high psychological distress including young adults, adults in low-income households, and Hispanics."
The survey used a scale to assess feelings of emotional suffering and symptoms of anxiety and depression in the past 30 days. The survey questions included in this analysis did not ask specifically about COVID-19. The scale, a validated measure of psychological distress, has been shown to accurately predict clinical diagnoses of serious mental illness.
Using NORC AmeriSpeak, a nationally representative online survey panel, the researchers analyzed survey responses of 1,468 adults ages 18 and older. They compared the measure of psychological distress in this survey sample from April 2020 to an identical measure from the 2018 National Health Interview Survey.
"The study suggests that the distress experienced during COVID-19 may transfer to longer-term psychiatric disorders requiring clinical care," says McGinty. "Health care providers, educators, social workers, and other front-line providers can help promote mental wellness and support."
https://www.sciencedaily.com/releases/2020/06/200603132550.htm
COVID-19: The downside of social distancing
April 24, 2020
Science Daily/Ludwig-Maximilians-Universität München
When faced with danger, humans draw closer together. Social distancing thwarts this impulse. Professor Ophelia Deroy from Ludwigs-Maximilians Universitaet in Munich (LMU) and colleagues argue that this dilemma poses a greater threat to society than overtly antisocial behavior.
The corona crisis presents countries around the globe with what is perhaps the greatest challenge most have faced since the Second World War. For one thing, the virus constitutes a truly global threat. In the absence of a vaccine, our primary defense against it consists in what is now termed 'social distancing' -- minimizing our contacts with others in public spaces. In an essay that appears in the leading journal Current Biology, an interdisciplinary team of authors that includes Professor Ophelia Deroy, who holds a Chair in the Philosophy of Mind at LMU and is affiliated with the Munich Neuroscience Center, underline the dilemma posed by measures designed to promote social distancing. "Hazardous conditions make us more -- not less -- social," Deroy says. "Coping with this contradiction is the biggest challenge we now face."
Seen from this point of view, our current problem lies not in egoistic reactions to the crisis or a refusal to recognize the risks, as images of banks of empty shelves in supermarkets or throngs of strollers in our public parks would have us believe. Deroy and her co-authors Chris Frith (a well-known social neurobiologist based at University College London) and Guillaume Dezecache (a social psychologist at the Université Clermont Auvergne) argue that such scenes are not representative. They emphasize that people instinctively tend to huddle together when faced with an acute danger -- in other words, they actively seek closer social contacts. Studies in the fields of neuroscience, psychology and evolutionary biology have already shown that we are not as egoist as some disciplines think. They continue to produce evidence which demonstrates that threatening situations make us even more cooperative and more likely to be socially supportive than we usually are.
"When people are afraid, they seek safety in numbers. But in the present situation, this impulse increases the risk of infection for all of us. This is the basic evolutionary conundrum that we describe," says Dezecache. The demands now being made by governments to self-isolate and follow social distancing guidelines are fundamentally at odd with our social instincts, and therefore represent a serious challenge for most people. "After all," says Deroy, "social contacts are not an 'extra', which we are at liberty to refuse. They are part of what we call normal." The essay's authors therefore contend that, because social distancing stands in opposition to our natural reaction to impending hazards, our social inclinations -- rather than antisocial reactions to rationally recognized threats -- now risk exacerbating the danger.
How then might we escape from this dilemma? According to Deroy, we need to revise what the Internet can offer. The argument goes as follows. In the pre-pandemic world, the Internet and social media were often looked upon as being decidedly unsocial. But in times like the present, they provide an acceptable and effective alternative to physical contact -- insofar as they enable social interactions in the absence of physical contiguity. Social media make it possible for large numbers of people to reach out virtually to neighbors, relatives, friends and other contacts. "Our innate inclinations are cooperative rather than egoistic. But access to the Internet makes it possible for us to cope with the need for social distancing," says Chris Frith.
"How well, and for how long, our need for social contact can be satisfied by social media remains to be seen," says Deroy. But she and her co-authors do have two important recommendations for policy-makers. First of all, they must acknowledge that the demand for social distancing is not only politically highly unusual : It runs counter to the evolved structure of human cognition. Secondly, nowadays, free access to the Internet is not only a prerequisite for freedom of speech. In the present situation, it is also making a positive contribution to public health. "This is an important message, given that the most vulnerable sections of society are often those who, owing to poverty, age and illness, have few social contacts." https://www.sciencedaily.com/releases/2020/04/200424132539.htm
'Feeling obligated' can impact relationships during social distancing
March 19, 2020
Science Daily/Michigan State University
In a time where many are practicing "social distancing" from the outside world, people are relying on their immediate social circles more than usual. Does a sense of obligation -- from checking on parents to running an errand for an elderly neighbor -- benefit or harm a relationship? A Michigan State University study found the sweet spot between keeping people together and dooming a relationship.
"We were looking to find whether obligation is all good or all bad," said William Chopik, assistant professor of psychology at MSU and co-author of the study. "When we started, we found that people were responding to types of obligations in different ways. People distinguished between requests that were massive obligations and requests that were simple. There's this point that obligation crosses over and starts to be harmful for relationships."
According to Jeewon Oh, MSU doctoral student and co-author of the study, obligation is sometimes the "glue that holds relationships together," but it often carries negative connotations.
"We found that some obligations were linked with greater depressive symptoms and slower increases in support from friends over time," Oh said. "However, other obligations were linked with both greater support and less strain from family and friends initially."
Chopik and Oh's findings suggest that there's a distinct point at which obligation pushes individuals to the brink of feeling burdened, which can start to harm their relationships.
"The line in our study is when it crosses over and starts to be either a massive financial burden or something that disrupts your day-to-day life," Chopik said. "While engaging in substantive obligation can benefit others and make someone feel helpful, it is still costly to a person's time, energy and money."
Until now, similar research showed inconsistencies in how obligation impacts relationships, which Chopik attributes to the spectrum of obligation. This spectrum ranges from light obligation, like keeping in touch with a friend, to substantive obligation, like lending that friend a considerable amount of money.
"In a way, major obligations violate the norms of friendships," Chopik said. "Interestingly, you don't see that violation as much in relationships with parents or spouses."
Chopik explained that friendships are viewed as low-investment, fun relationships that make people feel good.
"Our longest lasting friendships continue because we enjoy them. But if obligations pile up, it might compromise how close we feel to our friends," Chopik said. "Because friendships are a relationship of choice, people can distance themselves from friends more easily than other types of relationships when faced with burdensome obligations."
Additionally, substantive obligations may create strain in a friendship as we try to encourage our friends to do the same even when they might not be able to do so, Oh said.
"Although we may feel good when we do things for our friends, and our friends are grateful to us, we may start to feel like we are investing too much in that relationship," Oh said.
On the other end of the spectrum, light obligation creates what Chopik calls a "norm of reciprocity."
"Those light obligations make us feel better, make us happier and make our relationships stronger," Chopik said. "There's a sense that 'we're both in this together and that we've both invested something in the relationship.'"
That's why, among the best relationships, low-level acts of obligation don't feel like obligations at all. Small acts of kindness, which strengthen the bonds of our relationships, are done without any fuss or burden.
Still, some types of relationships can make even minor obligations seem daunting. If someone doesn't have a great relationship with a parent, a quick phone call to check in isn't enjoyable, it's an encumbrance.
"Even for things we would expect family members to do, some in the study did them begrudgingly," Chopik said.
Chopik and Oh's findings reveal a spectrum of obligations as diverse as the relationships one has in life.
"It's the little things you do that can really enhance a friendship, but asking too much of a friend can damage your relationship," Chopik said.
https://www.sciencedaily.com/releases/2020/03/200319125132.htm