Non-pharmaceutical intervention (epidemiology)

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In epidemiology, a non-pharmaceutical intervention (NPI) is any method used to reduce the spread of an epidemic disease without requiring pharmaceutical drug treatments. Examples of non-pharmaceutical interventions that reduce the spread of infectious diseases include wearing a face mask and staying away from sick people. [1]

Contents

The US Centers for Disease Control and Prevention (CDC) points to personal, community, and environmental interventions. [2] NPIs have been recommended for pandemic influenza at both local [3] and global levels [4] and studied at large scale during the 2009 swine flu pandemic [5] and the COVID-19 pandemic. [6] [7] [8] NPIs are typically used in the period between the emergence of an epidemic disease and the deployment of an effective vaccine. [9]

Types

Choosing to stay home to prevent the spread of symptoms of a potential sickness, covering coughs and sneezes, and washing one's hands regularly, are all examples of non-→pharmaceutical interventions. [10] Another example is when administrators of schools, workplaces, community areas, etc., take proper preventive actions and remind people to take precautions when need be in order to avoid the spread of disease. [10] Most NPIs are simple, requiring little effort to put into practice, and, if implemented correctly, could save many lives.[ citation needed ]

Personal protective measures

Hand hygiene

Hand washing can be done with soap and water or with alcohol-based hand sanitizers. Hand washing is a practice already in use in many countries in order to prevent the spread of communicable diseases. Although alcohol-based rubs may be too expensive in some settings, soap and water hand sanitization is one of the most cost-effective preventive measures. [9]

Respiratory etiquette

Respiratory etiquette refers to the methods a person uses to prevent transmission of disease when coughing or sneezing. This includes covering the mouth with the hand, elbow, or sleeve while in the process of coughing or sneezing, as well as proper disposal or washing of the contaminated material used to cover the mouth after a cough or sneeze has occurred. Like proper hand hygiene, this is a cost-effective intervention. [9]

Face masks

Face masks can be worn to reduce person-to-person transmission of respiratory disease. Medical masks are used in healthcare settings in some circumstances even during times when there is not a pandemic. During a pandemic, it is recommended that symptomatic individuals wear disposable medical grade masks at all times when exposed to others, and that asymptomatic members of the public wear face masks during severe pandemics to reduce transmission. The World Health Organization (WHO) recommended against the use of reusable cloth masks in 2019, [9] but in 2020 suggested their use by the general public when physical distancing is not feasible, as part of its "Do it all!" approach to the COVID-19 pandemic. [11]

Environmental measures

Surface and object cleaning

Germs can survive outside the body on hard surfaces for periods ranging from hours to weeks, depending on the virus and environmental conditions. The disinfection of high-touch surfaces with substances such as bleach or alcohol kills germs, preventing indirect contact transmission. Dirty surfaces should be washed before the use of disinfectant. [9] [12]

Ultraviolet lights

Ultraviolet (UV) light can be used to destroy micro-organisms that exist in the environment. The installation of UV light fixtures can be costly and time consuming; it is unlikely that they could be used at the outbreak of an epidemic. There are possible health concerns involving UV light, as it may cause cancer and eye problems. The WHO does not recommend its use. [9]

Increased ventilation

Increased ventilation of a room through opening a window or through mechanized ventilation systems may reduce transmission within the room. Although opening a window may introduce allergens and air pollution, or, in some climates, cold air, it is overall a cheap and effective type of intervention, and its advantages probably outweigh its disadvantages. [9]

Modifying humidity

Viruses such as influenza and coronavirus thrive in cold, dry environments, and increasing the humidity of a room may reduce their transmission. [13] Higher humidity, however, may cause mold and mildew, which may in turn cause respiratory problems. Humidifiers are also expensive and will probably be in short supply at the start of an epidemic. [9]

Social distancing measures

Contact tracing

Contact tracing involves identifying individuals with whom an infected person may have been in close contact, and notifying them that they may have been exposed to the infection. Contact tracing is a measure that has ethical implications, in that it involves invading the privacy of the infected person. It also brings with it a large resource cost, as it requires trained personnel to perform the tracing. Less wealthy countries may not be able to mobilize a contact tracing task force. Contact tracing is likely to lead to an increase in those in quarantine. Overall, it may be justified, in that it can reduce the spread of disease at the start of a pandemic, and allows early identification of cases in those who have been exposed to an infected person. [9]

Isolation of sick individuals

Infected individuals may be restricted in their movements or isolated from others, either at home or in a healthcare facility, or in another designated location. This may either be voluntary (self-isolation), or mandatory. Although voluntary self-isolation is considered to be a low ethical risk, as it is common practice in many areas for someone who is sick to stay at home, mandatory isolation brings with it ethical concerns, such as freedom of movement and social stigma. There is a higher risk that infected individuals who share their homes with others will transmit their disease, such as to a family member or roommate. An isolated individual may also be financially affected by their inability to go to work. Overall, isolation of the sick is widely accepted as an intervention type among health professionals and policy makers, although acceptance among the public varies. [9]

Quarantine of exposed individuals

Quarantine involves the voluntary or imposed confinement of potentially non-ill persons who have been exposed to an illness, regardless of whether they have contracted it. Quarantine will often happen at home, but it may happen elsewhere, such as aboard ships (maritime quarantine) or airlines (onboard quarantine). Like isolation of sick individuals, forced quarantine of exposed individuals brings with it ethical concerns, although in this case the concerns may be greater; quarantine involves restricting the movement of those who may otherwise be well, and in some cases may even cause them greater risk if they are quarantining with the sick person to whom they were exposed, such as a sick family member or roommate with whom they live. Like isolation, quarantine brings with it financial risk, because of work absenteeism. [9]

School measures and closures

Measures taken involving schools range from making changes to operations within schools to complete school closures. Lesser measures may involve reducing the density of students, such as by distancing desks, cancelling activities, reducing class sizes, or staggering class schedules. Sick students may be isolated from the greater student body, such as by having them stay at home or otherwise segregate them from other students.

More drastic measures include class dismissal, in which classes are cancelled but the school stays open to provide childcare to some children, and complete school closure. Both measures may be either reactive or proactive: In a reactive case, the measure takes place after an outbreak has occurred in the school; in a proactive case, the measure takes place in order to prevent spread within the community.

Closures of schools may affect the families of affected children, especially low-income families. Parents may be forced to miss work to care for their children, affecting financial stability; children may also miss out on free school meals, causing nutritional concerns. Long absences from schools because of closures can also have negative effects on students' education. [9]

Workplace measures and closures

Measures taken in the workplace include: remote work; paid leave; staggering shifts such that arrival, exit, and break times are different for each employee; reduced contact; and extended weekends.

Workplace closure is a more drastic measure. The financial effect of workplace closure on both the individual and the economy can be severe. When remote work is not possible, such as in essential services, businesses may not be able to comply with guidelines. In one simulation study school closure coupled with 50% absenteeism in the workplace would have had the highest financial impact of all the scenarios studied, although some studies have found that the combination would be effective in reducing both the attack rate and the height of an epidemic.

One benefit of workplace closure is that when used in conjunction with school closures they avoid the need for parents to make childcare arrangements for children who are staying away from school.

The WHO recommends workplace closure only in the case of extraordinarily severe epidemics and pandemics. [9]

Avoiding crowding

Avoiding crowding may involve: avoiding crowded areas such as shopping centres and transportation hubs; closing public spaces and banning large gatherings, such as sports events or religious activities; or setting a limit on small gatherings, such as limiting them to no more than a few people. There are negative consequences to the banning of gatherings; banning cultural or religious activities, for example, may prevent access to support in a time of crisis. Gatherings also allow sharing of information, which can provide comfort and reduce fear.

The WHO recommends this intervention only in moderate and severe epidemics and pandemics. [9]

Travel advice

Travel advice involves notifying potential travelers that they may be entering a zone that is affected by a disease outbreak. It allows informed decisions to be made before travel, and it increases awareness when the traveler is in the destination country. Public awareness campaigns have been used in the past for areas affected by infectious diseases such as dengue, malaria, Middle East respiratory syndrome, and H1N1 influenza. Although such awareness campaigns may reduce exposure among those traveling abroad, they may cause economic impact, owing to reduced travel in countries about which the advice has been issued. Overall, this intervention type is considered both feasible and acceptable. [9]

Entry and exit screening

Entry and exit screening involves screening travelers at ports of entry for symptoms of illness. Measures include: health declarations, in which travelers make a declaration that they have not recently had symptoms of illness; visual inspections of the traveler; and the use of non-contact thermography, in which a device such as a thermographic camera is used to measure the traveler's body temperature, in order to determine if they have a fever. Such a method may be circumvented by the traveler through the use of antipyretics before travel in order to reduce fever. More intensive measures such as molecular diagnostics and point-of-care rapid antigen detection tests may also be used, but they carry a high resource cost and may not be applicable to a large number of travelers. A substantial number of resources may be needed in order to train staff and acquire equipment.

Although there is probably no harm to the traveler by the use of this type of intervention, a limitation of it is that travelers may be asymptomatic on arrival and symptoms may not show until several days after entry, at which point they may have already exposed others to their illness. There are also ethical concerns involving invading the privacy of the traveler. Screening is considered by the WHO to be both acceptable and feasible, though they did not recommend its use in the case of influenza outbreak due to its inefficacy in identifying asymptomatic individuals. [9]

Internal travel restrictions

Travel within a country may be restricted in order to delay the spread of disease. Restriction of travel within a country is likely to slow the spread of disease, but not prevent it entirely. Its use would be most effective at the start of a localized and extraordinarily severe pandemic for only a short period of time. It would only be effective if the measures were strict: while a 90% restriction was projected to delay spread by one or two weeks, a 75% restriction saw no effect. An analysis of the spread of influenza in America following complete airline closures due to the September 11 attacks saw reduced spread by 13 days compared with previous years.

Restricting travel brings both ethical, and in many countries, legal challenges. Freedom of movement is considered in many places to be a human right, and its restriction may have an adverse effect, particularly among vulnerable populations, such as migrant workers and those traveling to seek medical attention. Although 37% of the Member States of the WHO included internal travel restrictions as part of their pandemic preparedness plan as of 2019, some of those countries may face legal challenges in implementing them, because of their own laws. Such restrictions may also bring economic effects because of disruption in the supply chain. [9]

Border closure

Border closure is a measure that involves complete or severe restriction of travel across borders. This had a beneficial effect in delaying the spread of cases of influenza during the 1918 influenza pandemic, and was predicted to delay epidemic spread between Hong Kong and mainland China by 3.5 weeks. While border closure is expected to slow the spread of infection, it is not expected to reduce the duration of an epidemic. Strict border closure in island nations could be effective, although supply chain probelms may cause adverse disruptions.

Supply chain problems due to border closure are likely to cause disruption of essential goods, such as food and medications, as well as serious economic effects. They may have adverse effects on the daily lives of individuals. Border closure also has serious ethical implications, because, like internal travel restrictions, it involves restricting the movements of individuals. It should only be used as a voluntary measure to the maximum extent possible. There may also be stigmatization of individuals from affected areas.

Border closure would be most feasible at the very start of a pandemic. The WHO recommended it only in extraordinary circumstances, and asked that they be notified by any nation implementing it. [9]

1918 influenza pandemic

Early use of face masks during the Spanish flu Precaution during the Spanish Influenza Epidemic would not permit anyone to ride on the street cars without wearing a mask, Seattle, Washington (ca.1918). Original from Library of Congress. Digitally enhanced by rawpixel. (50636591896).jpg
Early use of face masks during the Spanish flu

Non-→pharmaceutical interventions were widely adopted during the 1918 flu outbreak – most famously, the radical quarantine of Gunnison, Colorado resulted in sparing the town the worst of the earlier waves of the pandemic. [1] Interventions used included the wearing of face masks, isolation, quarantine, personal hygiene, use of disinfectants, and limits on public gatherings. At the time, the science behind NPIs was new, and was not applied consistently in every area. Retroactive studies on the outbreak have shown that the measures were effective in mitigating the spread of the infection. [14] [15]

The use of non-→pharmaceutical interventions during the 1918 flu pandemic also gave rise to new societal concerns. There was a growing awareness of "overreacting" and "under-reacting" among U.S. public health authorities, and these opposing perspectives often added to the uncertainties inherent in the epidemic. Likewise, public perceptions varied with respect to adherence to public health guidelines, giving rise to terms such as "mask slackers" and "careless consumptives." [16]

COVID-19

COVID-19 is a disease caused by the SARS-CoV-2 virus, which spread from China, creating a pandemic. [17] Several COVID-19 vaccines are now being used, 6.54 billion doses having been administered worldwide as of 12 October 2021. [18]

In the early stages of the COVID-19 pandemic, before vaccines had been developed, NPIs were key in mitigating infections and reducing COVID-19-related mortality. Some NPIs remained in place or were reinstituted for a time after vaccine rollout. [19] One report identified over 500 specific NPIs for controlling transmission and spread of the SARS-CoV-2 virus; most of these have been tried in practice. [8] Evidence suggests that highly effective strategies include closing schools and universities, [20] banning large gatherings, [20] and wearing face masks. [21]

See also

Related Research Articles

<span class="mw-page-title-main">Pandemic</span> Widespread, often global, epidemic of severe infectious disease

A pandemic is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. Widespread endemic diseases with a stable number of infected individuals such as recurrences of seasonal influenza are generally excluded as they occur simultaneously in large regions of the globe rather than being spread worldwide.

<span class="mw-page-title-main">Quarantine</span> Epidemiological intervention to prevent disease transmission

A quarantine is a restriction on the movement of people, animals and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have been exposed to a communicable disease, yet do not have a confirmed medical diagnosis. It is distinct from medical isolation, in which those confirmed to be infected with a communicable disease are isolated from the healthy population. Quarantine considerations are often one aspect of border control.

<i>Cordon sanitaire</i> (medicine) Quarantine of a geographic area

A cordon sanitaire is the restriction of movement of people into or out of a defined geographic area, such as a community, region, or country. The term originally denoted a barrier used to stop the spread of infectious diseases. The term is also often used metaphorically, in English, to refer to attempts to prevent the spread of an ideology deemed unwanted or dangerous, such as the containment policy adopted by George F. Kennan against the Soviet Union.

The Centers for Disease Control and Prevention, formed in 1946, is the leading national public health institute of the United States. It is a United States federal agency, under the United States Department of Health and Human Services. Its main goal is to protect public health and safety through the control and prevention of disease, injury, and disability in the US and internationally.

<span class="mw-page-title-main">Pandemic severity index</span> Proposed measure of the severity of influenza

The pandemic severity index (PSI) was a proposed classification scale for reporting the severity of influenza pandemics in the United States. The PSI was accompanied by a set of guidelines intended to help communicate appropriate actions for communities to follow in potential pandemic situations. Released by the United States Department of Health and Human Services (HHS) on February 1, 2007, the PSI was designed to resemble the Saffir-Simpson Hurricane Scale classification scheme. The index was replaced by the Pandemic Severity Assessment Framework in 2014, which uses quadrants based on transmissibility and clinical severity rather than a linear scale.

Protective sequestration, in public health, is social distancing measures taken to protect a small, defined, and still-healthy population from outsiders during an epidemic before the infection reaches that population. It is sometimes referred to as "reverse cordon sanitaire."

<span class="mw-page-title-main">Isolation (health care)</span> Measure taken to prevent contagious diseases from being spread

In health care facilities, isolation represents one of several measures that can be taken to implement in infection control: the prevention of communicable diseases from being transmitted from a patient to other patients, health care workers, and visitors, or from outsiders to a particular patient. Various forms of isolation exist, in some of which contact procedures are modified, and others in which the patient is kept away from all other people. In a system devised, and periodically revised, by the U.S. Centers for Disease Control and Prevention (CDC), various levels of patient isolation comprise application of one or more formally described "precaution".

<span class="mw-page-title-main">Influenza</span> Infectious disease

Influenza, commonly known as "the flu" or just "flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms begin one to four days after exposure to the virus and last for about two to eight days. Diarrhea and vomiting can occur, particularly in children. Influenza may progress to pneumonia from the virus or a subsequent bacterial infection. Other complications include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease.

<span class="mw-page-title-main">Social distancing</span> Infection control technique by keeping a distance from each other

In public health, social distancing, also called physical distancing, is a set of non-pharmaceutical interventions or measures intended to prevent the spread of a contagious disease by maintaining a physical distance between people and reducing the number of times people come into close contact with each other. It usually involves keeping a certain distance from others and avoiding gathering together in large groups.

<span class="mw-page-title-main">Airborne transmission</span> Disease transmission by airborne particles

Airborne transmission or aerosol transmission is transmission of an infectious disease through small particles suspended in the air. Infectious diseases capable of airborne transmission include many of considerable importance both in human and veterinary medicine. The relevant infectious agent may be viruses, bacteria, or fungi, and they may be spread through breathing, talking, coughing, sneezing, raising of dust, spraying of liquids, flushing toilets, or any activities which generate aerosol particles or droplets.

Influenza prevention involves taking steps that one can use to decrease their chances of contracting flu viruses, such as the Pandemic H1N1/09 virus, responsible for the 2009 flu pandemic.

<span class="mw-page-title-main">Neil Ferguson (epidemiologist)</span> British epidemiologist and researcher

Neil Morris Ferguson is a British epidemiologist and professor of mathematical biology, who specialises in the patterns of spread of infectious disease in humans and animals. He is the director of the Jameel Institute, and of the MRC Centre for Global Infectious Disease Analysis, and head of the Department of Infectious Disease Epidemiology in the School of Public Health and Vice-Dean for Academic Development in the Faculty of Medicine, all at Imperial College London.

<span class="mw-page-title-main">Workplace hazard controls for COVID-19</span> Prevention measures for COVID-19

Hazard controls for COVID-19 in workplaces are the application of occupational safety and health methodologies for hazard controls to the prevention of COVID-19. Vaccination is the most effective way to protect against severe illness or death from COVID-19. Multiple layers of controls are recommended, including measures such as remote work and flextime, increased ventilation, personal protective equipment (PPE) and face coverings, social distancing, and enhanced cleaning programs.

<span class="mw-page-title-main">Outbreak response</span> Measures to reduce the spread of an infectious disease

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.

The Imperial College COVID-19 Response Team is a group of experts from Imperial College London studying the COVID-19 pandemic and informing the government of the United Kingdom, and governments and public health agencies around the world. The team comprises scientists from the MRC Centre for Global Infectious Disease Analysis, the Jameel Institute, the Imperial College Business School and the Department of Mathematics. The Imperial College COVID-19 Response Team is led by Professor Neil Ferguson, Director of the Jameel Institute and MRC GIDA.

The MRC Centre for Global Infectious Disease Analysis is a Medical Research Council funded research centre at Imperial College London and a WHO collaborating centre. It is part of the Department of Infectious Disease Epidemiology at School of Public Health within the Imperial College Faculty of Medicine. Neil Ferguson is the director of the centre, along with four associate directors: Christl Donnelly, Azra Ghani, Nicholas Grassly, and Timothy Hallett. The centre also collaborates UK Health Protection Agency, and the US Centre for Disease Control. The centre's main research areas are disease outbreak analysis and modelling, vaccines, global health analytics, antimicrobial resistance, and developing methods and tools for studying these areas. The centre was previously called the MRC Centre for Outbreak Analysis and Modelling.

<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.

The Abdul Latif Jameel Institute for Disease and Emergency Analytics is a research institute at Imperial College London in the fields of epidemiology, mathematical modelling of infectious diseases and emergencies, environmental health, and health economics. Co-founded in 2019 by Imperial College London and Community Jameel, the Jameel Institute is housed in the School of Public Health, within the college's Faculty of Medicine. The mission of the Jameel Institute is "to combat threats from disease worldwide".

<span class="mw-page-title-main">Glossary of the COVID-19 pandemic</span> Glossary article for the COVID-19 pandemic

The COVID-19 pandemic has created and popularized many terms relating to disease and videoconferencing.

<span class="mw-page-title-main">Zero-COVID</span> COVID-19 elimination strategy

Zero-COVID, also known as COVID-Zero and "Find, Test, Trace, Isolate, and Support" (FTTIS), was a public health policy implemented by some countries, especially China, during the COVID-19 pandemic. In contrast to the "living with COVID-19" strategy, the zero-COVID strategy was purportedly one "of control and maximum suppression". Public health measures used to implement the strategy included as contact tracing, mass testing, border quarantine, lockdowns, and mitigation software in order to stop community transmission of COVID-19 as soon as it was detected. The goal of the strategy was to get the area back to zero new infections and resume normal economic and social activities.

References

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