Flattening the curve is apublic health strategy used to slow down the spread of aninfectious disease in order to prevent overwhelming health care systems. The curve being flattened refers to theepidemic curve, a visual representation of the number of infected people needing health care over time. During anepidemic, health care systems can become overwhelmed when the number of people infected exceeds their capacity to provide adequate care. Flattening the curve reduces the peak number of infected people requiring care at any one time, helping ensure that the healthcare system remains within its capacity to treat patients. This strategy gained widespread attention during the early stages of theCOVID-19 pandemic as governments sought to manage the spread of theSARS-CoV-2 virus.
The strategy relies on mitigation measures such ashand washing, use of face masks, andsocial distancing. A related concept is "raising the line", which involves increasing health care capacity[4] – for example, by expanding the availability ofintensive care unit (ICU) beds andventilators.[2] Flattening the curve and raising the line are complementary strategies that work together to reducemortality and ensure the health care system can continue providing care.
Flattening the curve is distinct from "zero-COVID" strategies, which aim to eliminatetransmission entirely. Instead, flattening the curve tolerates low levels ofcommunity transmission while aiming to minimize disruption and protect vulnerable populations.[5][6] These strategies may be pursued sequentially or simultaneously during different phases of an epidemic, particularly as population-level immunity is acquiredthrough infection orvaccination.[7]
Warnings about the risk of pandemics were repeatedly made throughout the 2000s and the 2010s by major international organisations including theWorld Health Organization (WHO) and theWorld Bank, especially after the2002–2004 SARS outbreak.[8] Governments, including those in theUnited States andFrance, both prior to the2009 swine flu pandemic, and during the decade following the pandemic, both strengthened their health care capacities and then weakened them.[9][10] 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 availableICU beds.[11] One majorpublic 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]
Non-pharmaceutical interventions such ashand washing,social distancing,isolation anddisinfection[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.[12]
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, providingtelemedicine, 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.[13]
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The concept was popular during the early months of the COVID-19 pandemic.[15]
According toVox, 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.[16] 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 resolvingshortages inpersonal protection equipment,face masks.[16]
According toThe Nation, territories with weak finances and health care capacity such asPuerto Rico facedan uphill battle to raise the line, and therefore a higher imperative pressure to flatten the curve.[17]
In March 2020,UC Berkeley Economics and Law professorAaron 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 theDefense Production Act to order manufacturing companies to produce the neededsanitizers,personal protective equipment,ventilators, and set up hundreds thousands to millions requiredhospital 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]
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