Flattening the curve

Last updated

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 (
{\textstyle \beta }
) by 76% SIR model anim.gif
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 the SARS-CoV-2 virus during 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.


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] As of April 2020, in the case of the COVID-19 pandemic, two key measures are to increase the numbers of available ICU beds and ventilators, which are in systemic shortage. [2] [ needs update ]


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. [6] 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. [7] [8] 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. [9] 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 intra-hospital spread. [4]

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. [10]

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. [12]

According to Vox, in order to move away from social distancing and return to normal, the US needs to flatten the curve by isolation and mass testing, and to raise the line. [13] Vox encourages 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. [13]

According to The Nation, territories with weak finances and health care capacity such as Puerto Rico face 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. [14] 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. [14] 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. [14] 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. [14]

In early May, the senior contributor on healthcare from Forbes posted, "Tenet Healthcare said its more than 60 hospitals are 'not being overwhelmed' by patients sickened by the Coronavirus strain COVID-19, the latest sign the U.S. healthcare system may be effectively coping with the pandemic," suggesting that the goal of flattening the curve to a point below health care capacity had met with initial success. [15] By 2021, the phrase "flatten the curve" had largely fallen out of medical messaging etymology. [16] [17]

See also

Related Research Articles

COVID-19 pandemic Ongoing global pandemic of coronavirus disease 2019

The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identified in Wuhan, China, in December 2019; a lockdown in Wuhan and other cities in Hubei province failed to contain the outbreak, and it spread to other parts of mainland China and around the world. The World Health Organization (WHO) declared a Public Health Emergency of International Concern on 30 January 2020, and a pandemic on 11 March 2020. Since 2021, variants of the virus have emerged and become dominant in many countries, with the Delta, Alpha and Beta variants being the most virulent. As of 19 September 2021, more than 228 million cases and 4.68 million deaths have been confirmed, making it one of the deadliest pandemics in history.

Social impact of the COVID-19 pandemic Indirect effects of the COVID-19 pandemic

The COVID-19 pandemic has had far-reaching consequences beyond the spread of the disease itself and efforts to quarantine it, including political, cultural, and social implications.

COVID-19 pandemic in the United Kingdom Ongoing COVID-19 viral pandemic in the UK

The COVID-19 pandemic in the United Kingdom is part of the worldwide pandemic of coronavirus disease 2019. The virus reached the UK in late January 2020. As of 12 August 2021, there had been more than 6.1 million confirmed cases and 120,701 deaths among people who had recently tested positive – the world's twenty-second-highest death rate by population and the second-highest death toll in Europe after Russia. There has been some disparity between the outbreak's severity in England, Scotland, Wales and Northern Ireland – health in the UK is devolved, with each constituent country having its own publicly-funded healthcare system operated by devolved governments.

The COVID-19 pandemic in Bahrain is part of the worldwide pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2. The virus was confirmed to have reached Bahrain on 21 February 2020.

COVID-19 pandemic in Egypt Ongoing COVID-19 viral pandemic in Egypt

The COVID-19 pandemic in Egypt is part of the worldwide pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2. The virus was confirmed to have reached Egypt on 14 February 2020.

COVID-19 pandemic in Slovenia Ongoing COVID-19 viral pandemic in Slovenia

The COVID-19 pandemic in Slovenia is part of the pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2. The virus spread to Slovenia on 4 March 2020, when the first case was confirmed. It was an imported case transmitted by a tourist traveling from Morocco via Italy, which was the center of the SARS-CoV-2 in Europe at the time.

COVID-19 pandemic in California Ongoing COVID-19 viral pandemic in California, United States

Ten of the first twenty confirmed COVID-19 cases in the United States occurred in California, the first of which was confirmed on January 26, 2020. All of the early confirmed cases were persons who had recently travelled to China, as testing was restricted to this group. On January 29, 2020, as disease containment protocols were still being developed, the U.S. Department of State evacuated 195 persons from Wuhan, China aboard a chartered flight to March Air Reserve Base in Riverside County, and in the process may have contributed to spread within the state and the US at large. On February 5, 2020, the U.S. evacuated 345 more citizens from Hubei Province to two military bases in California, Travis Air Force Base in Solano County and Marine Corps Air Station Miramar, San Diego, where they were quarantined for 14 days. A state of emergency was declared in the state on March 4, 2020 and as of February 24, 2021 remains in effect. A mandatory statewide stay-at-home order was issued on March 19, 2020 that was ended on January 25, 2021. On April 6, 2021, the state announced plans to fully reopen the economy by June 15, 2021.

COVID-19 pandemic in Guinea-Bissau Ongoing COVID-19 viral pandemic in Guinea-Bissau

The COVID-19 pandemic in Guinea-Bissau is part of the worldwide pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2. The virus was confirmed to have reached Guinea-Bissau in March 2020.

COVID-19 pandemic in Idaho Ongoing COVID-19 viral pandemic in Idaho, United States

The first case relating to the COVID-19 pandemic in Idaho was confirmed on March 13, 2020, when a Boise woman tested positive. As of September 14, 2021, there have been 237,000 confirmed cases and 2,505 deaths within Idaho, while 757,938 people have been fully vaccinated.

COVID-19 pandemic in Yemen Ongoing COVID-19 viral pandemic in Yemen

The first confirmed case relating to the COVID-19 pandemic in Yemen was announced on 10 April 2020 with an occurrence in Hadhramaut. Organizations called the news a "devastating blow" and a "nightmare scenario" given the country's already dire humanitarian situation.

COVID-19 pandemic in Scotland Ongoing COVID-19 viral pandemic in Scotland

The COVID-19 pandemic was first confirmed to have spread to Scotland on 1 March 2020 with the positive COVID-19 test of a male Tayside resident who had recently travelled between Scotland and northern Italy. The first reported case of community transmission was on 11 March 2020 and the first reported coronavirus death in Scotland was on 13 March 2020.

Shortages of medical materials, manufacturing and consumer goods caused by the COVID-19 pandemic quickly became a major issue worldwide, as did interruptions to the global supply chain, which has challenged supply chain resilience across the globe. Shortages of personal protective equipment, such as medical masks and gloves, face shields, and sanitizing products, along with hospital beds, ICU beds, oxygen therapy equipment, ventilators, and ECMO devices were reported in most countries.

NHS Nightingale Hospital London Temporary NHS COVID-19 hospital set up in ExCeL London

The NHS Nightingale Hospital London is the first of the NHS Nightingale Hospitals: temporary hospitals set up by NHS England for the COVID-19 pandemic. It is housed in the ExCeL London convention centre in East London, and has an initial capacity for 500 patients, with potential for 4,000. The hospital was rapidly planned and constructed, being formally opened on 3 April and receiving its first patients on 7 April 2020.

Outbreak response

Outbreak response or outbreak control measures are acts which attempt to minimize the spread of or effects of a disease outbreak. Outbreak response includes aspects of general disease control such as maintaining adequate hygiene, but may also include responses that extend beyond traditional healthcare settings and are unique to an outbreak, such as physical distancing, contact tracing, mapping of disease clusters, or quarantine. Some measures such as isolation are also useful in preventing an outbreak from occurring in the first place.

COVID-19 pandemic in England Ongoing COVID-19 viral pandemic in England

The COVID-19 pandemic was first confirmed to have spread to England with two cases among Chinese nationals staying in a hotel in York on 31 January 2020. The two main public bodies responsible for health in England are NHS England and Public Health England. NHS England oversees the budget, planning, delivery and day-to-day operation of the commissioning side of the NHS in England while PHE's mission is "to protect and improve the nation’s health and to address inequalities". As of 14 September 2021, there have been 6,237,505 total cases and 117,955 deaths in England. In January 2021 it was estimated around 22% of people in England have had COVID-19.

Exercise Cygnus was a three-day simulation exercise carried out by NHS England in October 2016 to estimate the impact of a hypothetical H2N2 influenza pandemic on the United Kingdom. It aimed to identify strengths and weaknesses within the United Kingdom health system and emergency response chain by putting it under significant strain, providing insight on the country's resilience and any future ameliorations required. It was conducted by Public Health England representing the Department of Health and Social Care, as part of a project led by the "Emergency Preparedness, Resilience and Response Partnership Group". Twelve government departments across Scotland, Wales and Northern Ireland, as well as local resilience forums (LRFs) participated. More than 950 workers from those organisations, prisons and local or central government were involved during the three-day simulation, and their ability to cope under situations of high medical stress was tested.

Impact of the COVID-19 pandemic on healthcare workers

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.

There is no specific, effective treatment or cure for coronavirus disease 2019 (COVID-19), the disease caused by the SARS-CoV-2 virus. One year into the pandemic, highly effective vaccines have now been introduced and are beginning to slow the spread of SARS-CoV-2; however, for those awaiting vaccination, as well as for the estimated millions of immunocompromised persons who are unlikely to respond robustly to vaccination, treatment remain important. Thus, the lack of progress developing effective treatments means that the cornerstone of management of COVID-19 has been supportive care, which includes treatment to relieve symptoms, fluid therapy, oxygen support and prone positioning as needed, and medications or devices to support other affected vital organs.

Public health mitigation of COVID-19 Measures to halt the spread of the respiratory disease among populations

Speed and scale are key to mitigation of COVID-19, due to the fat-tailed nature of pandemic risk and the exponential growth of COVID-19 infections. For mitigation to be effective, (a) chains of transmission must be broken as quickly as possible through screening and containment, (b) health care must be available to provide for the needs of those infected, and (c) contingencies must be in place to allow for effective rollout of (a) and (b).

Hussain Dawood Pledge Private donation and initiative to fight against the COVID-19 pandemic in Pakistan

The Hussain Dawood Pledge (HD-Pledge) is one of the biggest private donations and initiatives to fight against the COVID-19 pandemic in Pakistan. Hussain Dawood, on behalf of Engro, Dawood Hercules and his family pledged on 2 April 2020 a contribution in services, kind, and cash of Pakistani rupee (PKR) 1 billion. The contribution became public a day after Prime Minister Imran Khan announced the coronavirus relief fund to fight the pandemic and urged everyone to donate.


  1. Wiles, Siouxsie (9 March 2020). "The three phases of Covid-19—and how we can make it manageable". The Spinoff . Morningside, Auckland, New Zealand. Archived from the original on 27 March 2020. Retrieved 9 March 2020.
  2. 1 2 3 4 Barclay, Eliza (7 April 2020). "Chart: The US doesn't just need to flatten the curve. It needs to "raise the line."". Vox . Archived from the original on 7 April 2020. Retrieved 7 April 2020.
  3. Maier, Benjamin F.; Brockmann, Dirk (15 May 2020). "Effective containment explains subexponential growth in recent confirmed COVID-19 cases in China". Science. 368 (6492): 742–746. Bibcode:2020Sci...368..742M. doi:10.1126/science.abb4557. PMC   7164388 . PMID   32269067. ("...initial exponential growth expected for an unconstrained outbreak.")
  4. 1 2 3 4 5 6 7 8 9 Beating Coronavirus: Flattening the Curve, Raising the Line (YouTube video). Retrieved 12 April 2020.
  5. 1 2 Gelardi, Chris (9 April 2020). "Colonialism Made Puerto Rico Vulnerable to Coronavirus Catastrophe". The Nation . ISSN   0027-8378. Archived from the original on 12 April 2020. Retrieved 12 April 2020.
  6. "Wanted: world leaders to answer the coronavirus pandemic alarm". South China Morning Post. 31 March 2020. Archived from the original on 9 April 2020. Retrieved 6 April 2020.
  7. Manjoo, Farhad (25 March 2020). "Opinion | How the World's Richest Country Ran Out of a 75-Cent Face Mask". The New York Times. ISSN   0362-4331. Archived from the original on 25 March 2020. Retrieved 25 March 2020.
  8. "Pénurie de masques : une responsabilité partagée par les gouvernements" [Lack of masks: a responsibility shared by governments]. Public Senat (in French). 23 March 2020. Archived from the original on 9 April 2020. Retrieved 6 April 2020.
  9. Imperial College COVID-19 Response Team (16 March 2020). "Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand" (PDF). Archived (PDF) from the original on 16 March 2020. Retrieved 23 March 2020 via imperial.ac.uk.
  10. Dudley, Joshua. "Q&A: Dr. Rishi Desai Talks To Medical Professionals About What We Can Learn From COVID-19". Forbes. Archived from the original on 12 June 2020. Retrieved 18 June 2020.
  11. Stevens, Harry (14 March 2020). "These simulations show how to flatten the coronavirus growth curve". The Washington Post . Archived from the original on 30 March 2020. Retrieved 29 March 2020.
  12. Roberts, Siobhan (27 March 2020). "Flattening the Coronavirus Curve". The New York Times. ISSN   0362-4331. Archived from the original on 11 April 2020. Retrieved 12 April 2020.
  13. 1 2 Lopez, German (10 April 2020). "Why America is still failing on coronavirus testing". Vox.com . Archived from the original on 20 December 2020. Retrieved 12 April 2020.
  14. 1 2 3 4 Edlin, Aaron (March 2020). "Don't just flatten the curve: Raise the line" (PDF). p. 2. Archived (PDF) from the original on 18 April 2020. Retrieved 12 April 2020 via berkeley.edu.
  15. Japsen, Bruce (4 May 2020). "Hospital Operator Tenet Healthcare 'Not Overwhelmed' with Coronavirus Cases". Forbes. Archived from the original on 11 May 2020. Retrieved 10 May 2020.
  16. "We haven't failed on the virus". Australian Financial Review. 29 June 2021. Retrieved 2 July 2021.
  17. Scott, Dylan (31 December 2020). "Flattening the curve worked — until it didn't". Vox. Retrieved 2 July 2021.