Flattening the curve

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20200403 Flatten the curve animated GIF.gif
Measures such as hand washing, social distancing and face masks reduce and delay the peak of active cases, allowing more time for healthcare capacity to increase and better cope with patient load. [1] Time gained through thus flattening the curve can be used to raise the line of healthcare capacity to better meet surging demand. [2]
20200609 Effect of pandemic containment measures.gif
Without pandemic containment measures—such as social distancing, vaccination, and use of face masks—pathogens can spread exponentially. [3] This graphic illustrates how early adoption of containment measures tends to protect wider swaths of the population, thus reducing and delaying the peak of active cases.
SIR model showing the impact of reducing the infection rate (
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SIR model showing the impact of reducing the infection rate () by 76%

Flattening the curve is a public health strategy to slow down the spread of an epidemic, used against the SARS-CoV-2 virus during the early stages of the COVID-19 pandemic. The curve being flattened is the epidemic curve, a visual representation of the number of infected people needing health care over time. During an epidemic, a health care system can break down when the number of people infected exceeds the capability of the health care system's ability to take care of them. Flattening the curve means slowing the spread of the epidemic so that the peak number of people requiring care at a time is reduced, and the health care system does not exceed its capacity. Flattening the curve relies on mitigation techniques such as hand washing, use of face masks and social distancing.

Contents

A complementary measure is to increase health care capacity, to "raise the line". [4] As described in an article in The Nation , "preventing a health care system from being overwhelmed requires a society to do two things: 'flatten the curve'—that is, slow the rate of infection so there aren't too many cases that need hospitalization at one time—and 'raise the line'—that is, boost the hospital system's capacity to treat large numbers of patients." [5] During 2020, in the early stages of the COVID-19 pandemic, two key measures were to increase the numbers of available ICU beds and ventilators, which were in systemic shortage. [2] [ needs update ]

Experts differentiate between "zero-COVID", which is an elimination strategy taken by China, and "flattening the curve", a mitigation strategy that attempts to lessen the effects of the virus on society as much as possible, but still tolerates low levels of transmission within the community. [6] [7] These two initial strategies can be pursued sequentially or simultaneously during the acquired immunity phase through natural and vaccine-induced immunity. [8]

Background

Warnings about the risk of pandemics were repeatedly made throughout the 2000s and the 2010s by major international organisations including the World Health Organization (WHO) and the World Bank, especially after the 2002–2004 SARS outbreak. [9] Governments, including those in the United States and France, both prior to the 2009 swine flu pandemic, and during the decade following the pandemic, both strengthened their health care capacities and then weakened them. [10] [11] At the time of the COVID-19 pandemic, health care systems in many countries were functioning near their maximum capacities. [4] [ better source needed ]

In a situation like this, when a sizable new epidemic emerges, a portion of infected and symptomatic patients create an increase in the demand for health care that has only been predicted statistically, without the start date of the epidemic nor the infectivity and lethality known in advance. [4] If the demand surpasses the capacity line in the infections per day curve, then the existing health facilities cannot fully handle the patients, resulting in higher death rates than if preparations had been made. [4]

An influential UK study showed that an unmitigated COVID-19 response in the UK could have required up to 46 times the number of available ICU beds. [12] One major public health management challenge is to keep the epidemic wave of incoming patients needing material and human health care resources supplied in a sufficient amount that is considered medically justified. [4]

Flattening the curve

Queue markers at a shopping mall in Bangkok as a social distancing practicing Queue during COVID-19 must be social distancing at ICONSIAM.jpg
Queue markers at a shopping mall in Bangkok as a social distancing practicing

Non-pharmaceutical interventions such as hand washing, social distancing, isolation and disinfection [4] reduce the daily infections, therefore flattening the epidemic curve. A successfully flattened curve spreads health care needs over time and the peak of hospitalizations under the health care capacity line. [2] Doing so, resources, be it material or human, are not exhausted and lacking. In hospitals, it for medical staff to use the proper protective equipment and procedures, but also to separate contaminated patients and exposed workers from other populations to avoid patient-to-doctor or patient-to-patient spreading. [4] The origins of the expression date back to 2007, though during the COVID pandemic the expression became a repeated "sound bite" used by numerous medical and non-medical individuals in the media. [13]

Raising the line

Along with the efforts to flatten the curve is the need for a parallel effort to "raise the line", to increase the capacity of the health care system. [2] Healthcare capacity can be raised by raising equipment, staff, providing telemedicine, home care and health education to the public. [4] Elective procedures can be cancelled to free equipment and staffs. [4] Raising the line aims to provide adequate medical equipment and supplies for more patients. [14]

During the COVID-19 pandemic

Simulations comparing rate of spread of infection, and number of deaths due to overrun of hospital capacity, when social interactions are "normal" (left, 200 people moving freely) and "distanced" (right, 25 people moving freely).
Green = Healthy, uninfected individuals
Red = Infected individuals
Blue = Recovered individual
Black = Dead individuals Katapult importance social distancing.gif
Simulations comparing rate of spread of infection, and number of deaths due to overrun of hospital capacity, when social interactions are "normal" (left, 200 people moving freely) and "distanced" (right, 25 people moving freely).
Green = Healthy, uninfected individuals
Red = Infected individuals
Blue = Recovered individual
Black = Dead individuals

The concept was popular during the early months of the COVID-19 pandemic. [16]

According to Vox, in order to move away from social distancing and return to normal, the US needed to flatten the curve by isolation and mass testing, and to raise the line. [17] Vox encouraged building up health care capability including mass testing, software and infrastructures to trace and quarantine infected people, and scaling up cares including by resolving shortages in personal protection equipment, face masks. [17]

According to The Nation, territories with weak finances and health care capacity such as Puerto Rico faced an uphill battle to raise the line, and therefore a higher imperative pressure to flatten the curve. [5]

In March 2020, UC Berkeley Economics and Law professor Aaron Edlin commented that ongoing massive efforts to flatten the curve supported by trillions dollars emergency package should be matched by equal efforts to raise the line and increase health care capacity. [18] Edlin called for an activation of the Defense Production Act to order manufacturing companies to produce the needed sanitizers, personal protective equipment, ventilators, and set up hundreds thousands to millions required hospital beds. [18] Standing in March 2020 estimates, Edlin called for the construction of 100-300 emergency hospitals to face what he described as "the largest health catastrophe in 100 years" and to adapt health care legislation preventing emergency practices needed in time of pandemics. [18] Edlin pointed out proposed stimulus package as oriented toward financial panics, while not providing sufficient funding for the core issue of a pandemic: health care capability. [18]

By 2021, the phrase "flatten the curve" had largely fallen out of medical messaging etymology. [19] [20]

See also

Related Research Articles

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<span class="mw-page-title-main">COVID-19 pandemic</span> Pandemic caused by SARS-CoV-2

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an outbreak in Wuhan, China, in December 2019. It spread to other areas of Asia, and then worldwide in early 2020. The World Health Organization (WHO) declared the outbreak a public health emergency of international concern (PHEIC) on 30 January 2020, and assessed the outbreak had become a pandemic on 11 March.

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The COVID-19 pandemic in Taiwan was a part of the worldwide pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2. As of 19 March 2023 in Taiwan, 10,231,343 are confirmed cases, including 18,775 deaths.

<span class="mw-page-title-main">COVID-19 pandemic in the United Kingdom</span>

The COVID-19 pandemic in the United Kingdom is a part of the worldwide pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In the United Kingdom, it has resulted in 24,940,688 confirmed cases, and is associated with 232,112 deaths.

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The COVID-19 pandemic in the Czech Republic was a part of the worldwide pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2. On 12 January 2020, the World Health Organization (WHO) confirmed that a novel coronavirus was the cause of a respiratory illness in a cluster of people in Wuhan City, Hubei Province, China, which was reported to the WHO on 31 December 2019.

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<span class="mw-page-title-main">COVID-19 pandemic in California</span>

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<span class="mw-page-title-main">COVID-19 pandemic in Scotland</span>

The COVID-19 pandemic in Scotland is part of the COVID-19 pandemic of coronavirus disease-2019, caused by the virus SARS-CoV-2. The first case of COVID-19 was confirmed in Scotland on 1 March 2020. Community transmission was first reported on 11 March 2020, and the first confirmed death was on 13 March 2020.

<span class="mw-page-title-main">Shortages related to the COVID-19 pandemic</span> Medical material and other goods shortages caused by the COVID-19 pandemic

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<span class="mw-page-title-main">Face masks during the COVID-19 pandemic</span> Health control procedure against COVID-19

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<span class="mw-page-title-main">Impact of the COVID-19 pandemic on hospitals</span> Consequences of COVID-19 pandemic for hospitals

The COVID-19 pandemic has impacted hospitals around the world. Many hospitals have scaled back or postponed non-emergency care. This has medical consequences for the people served by the hospitals, and it has financial consequences for the hospitals. Health and social systems across the globe are struggling to cope. The situation is especially challenging in humanitarian, fragile and low-income country contexts, where health and social systems are already weak. Health facilities in many places are closing or limiting services. Services to provide sexual and reproductive health care risk being sidelined, which will lead to higher maternal mortality and morbidity. The pandemic also resulted in the imposition of COVID-19 vaccine mandates in places such as California and New York for all public workers, including hospital staff.

<span class="mw-page-title-main">Impact of the COVID-19 pandemic on healthcare workers</span>

The COVID-19 pandemic has impacted healthcare workers physically and psychologically. Healthcare workers are more vulnerable to COVID-19 infection than the general population due to frequent contact with infected individuals. Healthcare workers have been required to work under stressful conditions without proper protective equipment, and make difficult decisions involving ethical implications. Health and social systems across the globe are struggling to cope. The situation is especially challenging in humanitarian, fragile and low-income country contexts, where health and social systems are already weak. Services to provide sexual and reproductive health care risk being sidelined, which will lead to higher maternal mortality and morbidity.

<span class="mw-page-title-main">Source control (respiratory disease)</span> Strategy for reducing disease transmission

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<span class="mw-page-title-main">Public health mitigation of COVID-19</span> Measures to halt the spread of the respiratory disease among populations

Part of managing an infectious disease outbreak is trying to delay and decrease the epidemic peak, known as flattening the epidemic curve. This decreases the risk of health services being overwhelmed and provides more time for vaccines and treatments to be developed. Non-pharmaceutical interventions that may manage the outbreak include personal preventive measures such as hand hygiene, wearing face masks, and self-quarantine; community measures aimed at physical distancing such as closing schools and cancelling mass gathering events; community engagement to encourage acceptance and participation in such interventions; as well as environmental measures such surface cleaning. It has also been suggested that improving ventilation and managing exposure duration can reduce transmission.

<span class="mw-page-title-main">United States responses to the COVID-19 pandemic</span> Actions by the United States regarding the COVID-19 pandemic

The United States' response to the COVID-19 pandemic with consists of various measures by the medical community; the federal, state, and local governments; the military; and the private sector. The public response has been highly polarized, with partisan divides being observed and a number of concurrent protests and unrest complicating the response.

<span class="mw-page-title-main">United Kingdom responses to the COVID-19 pandemic</span> Actions by the United Kingdom regarding the COVID-19 pandemic

The United Kingdom's response to the COVID-19 pandemic consists of various measures by the healthcare community, the British and devolved governments, the military and the research sector.

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