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Part of managing an infectious disease outbreak is trying to delay and decrease the epidemic peak, known as flattening the epidemic curve.[1] This decreases the risk of health services being overwhelmed and provides more time for vaccines and treatments to be developed.[1] 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.[5] It has also been suggested that improving ventilation and managing exposure duration can reduce transmission.[6][7]
During early outbreaks, speed and scale were considered key to mitigation of COVID-19, due to the fat-tailed nature of pandemic risk and the exponential growth of COVID-19 infections.[8] 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).[citation needed]
By May 2023, in most countries restrictions had been lifted and everyday life had returned to how it was before the pandemic due to improvement in the pandemic's situation.[9][10]
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More drastic actions aimed at containing the outbreak were taken in China once the severity of the outbreak became apparent, such as quarantining entire cities or imposing strict travel bans.[11] Other countries also adopted a variety of measures aimed at limiting the spread of the virus, including resorting to states of emergency.[12] South Korea introduced the mass screening and localised quarantines and issued alerts on the movements of infected individuals. Singapore provided financial support for those infected who quarantined themselves and imposed large fines for those who failed to do so. Taiwan increased face mask production and penalised hoarding of medical supplies.[13] Thezero-COVID approach aims to prevent viral transmission, using a number of different measures, including vaccination andnon-pharmaceutical interventions such as contact-tracing and quarantine. Different combinations of measures are used during the initial containment phase, when the virus is first eliminated from a region, and the sustained containment phase, when the goal is to prevent reestablishment of viral transmission within the community.[14] Experts differentiate between zero-COVID, which is an elimination strategy, andmitigation strategies that attempt to lessen the effects of the virus on society, but which still tolerate some level of transmission within the community.[15][16] These initial strategies can be pursued sequentially or simultaneously during theacquired immunity phase through natural andvaccine-induced immunity.[17]
Simulations for Great Britain and the United States show that mitigation (slowing but not stopping epidemic spread) and suppression (reversing epidemic growth) have major challenges. Optimal mitigation policies might reduce peak healthcare demand by two-thirds and deaths by half, but still result in hundreds of thousands of deaths and overwhelmed health systems. Suppression can be preferred but needs to be maintained for as long as the virus is circulating in the human population (or until a vaccine becomes available), as transmission otherwise quickly rebounds when measures are relaxed. Until now, the evidence for public health (nonpharmaceutical) interventions such as social distancing, school closure, and case isolation comes mainly fromepidemiological compartmental models and, in particular,agent-based models (ABMs).[18] Such models have been criticized for being based on simplifying and unrealistic assumptions.[19][20] Still, they can be useful in informing decisions regarding mitigation and suppression measures in cases when ABMs are accurately calibrated.[21] An Argentinian modelling study asserted that complete lockdowns and healthcare system overextension could be avoided if 45 percent of asymptomatic patients were detected and isolated.[22] Long-term intervention to suppress the pandemic has considerable social and economic costs.[23]
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In August 2020, a working paper by theNational Bureau of Economic Research (NBER) questioned major effects of many mitigation and suppression measures. The authors compared the development of casualties connected to SARS-CoV-2 until July 2020, in 25 US states and 23 countries that had counted more than 1.000 overall deaths each. From the date a state passed a threshold of 25 deaths, the statistical study observed a largely uniform development, independently from type and time frame of governmental interactions. Thus, the growth rate of casualties dropped to zero within 20–30 days, and thevariability between regions was low, except at the beginning of the epidemics. The authors computed the effectivereproduction numberReff with the aid of different models like theSIR model, and found it hovering around one everywhere after the first 30 days of the epidemic. Hence, they did not findevidence for an influence of lockdowns, travel restrictions or quarantines on virus transmission.[24] For contradicting studies, they assume anomitted variable bias. Candidates for ignored effects could be voluntarysocial distancing, the structure ofsocial interactionnetworks (some people contact more networks faster than others), and a natural tendency of an epidemics to spread quickly at first and slow down, which has been observed in formerInfluenza pandemics, but not yet completely understood. The reviewer Stephen C. Miller concludes “that human interaction does not conform to simple epidemiological models”.[25][24]
Many reviews find high efficacy of mitigation measures such as vaccines, face masks and social distancing. For instance, a systematic review and meta-analysis found thatmask-wearing cuts the incidence ofCOVID-19 by 53% overall.[26][27] The efficacy may also be substantially higher, especially if certain types of masks are worn or under specific conditions and settings.
Contact tracing is an important method for health authorities to determine the source of infection and to prevent further transmission.[28] The use of location data from mobile phones by governments for this purpose has prompted privacy concerns, withAmnesty International and more than a hundred other organisations issuing a statement calling for limits on this kind of surveillance.[29]
An unincentivized and always entirely voluntary use of such digital contact tracing apps by the public was found to be low[30][31][32] even if the apps are built to preserve privacy (which may however compete with alternative domestic apps that don't do so and can't always be used), leading to low usefulness of the software for pandemic mitigation as of April 2021. A lack of possible features, prevalent errors and possibly other issues reduced their usefulness further.[33] Use of such an app in general or during specific times is in many or all cases not provable or requirable.
Moreover, contact-tracing apps may be designed criteria (<1 metre; and > 15 minutes contact) insufficient for controlling danger.[34]
Several mobile apps have been implemented or proposed for voluntary use, and as of 7 April 2020 more than a dozen expert groups were working on privacy-friendly solutions such as usingBluetooth to log a user's proximity to other cellphones.[29] (Users are alerted if they have been near someone who subsequently tests positive.)[29]
On 10 April 2020, Google andApple jointly announced an initiative for privacy-preserving contact tracing based on Bluetooth technology andcryptography.[35][36] The system is intended to allow governments to create official privacy-preserving coronavirus tracking apps, with the eventual goal of integration of this functionality directly into theiOS andAndroid mobile platforms.[37] In Europe and in the U.S.,Palantir Technologies is also providing COVID-19 tracking services.[38]
In February 2020, China launched amobile app to deal with the disease outbreak.[39] Users are asked to enter their name and ID number. The app can detect 'close contact' using surveillance data and therefore a potential risk of infection. Every user can also check the status of three other users. If a potential risk is detected, the app not only recommends self-quarantine, it also alerts local health officials.[40]
Big data analytics on cellphone data,facial recognition technology,mobile phone tracking, andartificial intelligence are used to track infected people and people whom they contacted in South Korea, Taiwan, and Singapore.[41][42] In March 2020, the Israeli government enabled security agencies to track mobile phone data of people supposed to have coronavirus. According to the Israeli government, the measure was taken to enforce quarantine and protect those who may come into contact with infected citizens. The Association for Civil Rights in Israel, however, said the move was "a dangerous precedent and a slippery slope".[43] Also in March 2020,Deutsche Telekom shared aggregated phone location data with the German federal government agency,Robert Koch Institute, to research and prevent the spread of the virus.[44] Russia deployed facial recognition technology to detect quarantine breakers.[45] Italian regional health commissionerGiulio Gallera said he has been informed by mobile phone operators that "40% of people are continuing to move around anyway".[46] The German Government conducted a 48-hour weekendhackathon, which had more than 42,000 participants.[47][48] Three million people in the UK used an app developed byKing's College London and Zoe to track people with COVID-19 symptoms.[49][50] The president of Estonia,Kersti Kaljulaid, made a global call for creative solutions against the spread of coronavirus.[51]
Increasing capacity and adapting healthcare for the needs of COVID-19 patients is described by the WHO as a fundamental outbreak response measure.[52] The ECDC and the European regional office of the WHO have issued guidelines for hospitals andprimary healthcare services for shifting of resources at multiple levels, including focusing laboratory services towards COVID-19 testing, cancellingelective procedures whenever possible, separating and isolating COVID-19 positive patients, and increasingintensive care capabilities by training personnel and increasing the number of availableventilators and beds.[52][53] In addition, in an attempt to maintain physical distancing, and to protect both patients and clinicians, in some areas non-emergency healthcare services are being provided virtually.[54][55][56]
There are research-based developments that aim to mitigate COVID-19 spread beyondvaccines,repurposed andnew medications and similar conventional measures.
Researchers investigate for safe ways ofpublic transport during the COVID-19 pandemic.[57][58]
Novel vaccine passports have been developed.
Researchers are developing face-masks which could be more effective at reducing SARS-CoV-2 spread than existing ones and/or have other desired properties such asbiodegradability and better breathability.[59][60][61][62][63][64] Some are also researching attachments to existing face-masks to make them more effective[63] or to add self-cleaning features.[63] The pandemic has increased efforts to develop such masks and some have received government grants for their development.[63]
Ventilation and air cleaners are also the subject of research and development.[65][66]
Researchers report the development ofchewing gums that couldmitigate COVID-19 spread. The ingredients –CTB-ACE2 proteins grown via plants – bind to the virus.[67][68]
On 23 April 2020,NASA reported building, in 37 days, a ventilator (called VITAL).[69][70] On April 30, NASA reported receiving fast-track approval for emergency use by theUnited States Food and Drug Administration for the new ventilator.[71] As of March 2020[update], 26 manufacturers around the world have been licensed to make the device.[72] TheCOVID-19 pandemic increased the demand for oxygen concentrators. During the pandemicopen source oxygen concentrators were developed, locally manufactured – with prices below imported products – and used, especially duringa COVID-19 pandemic wave in India.[73][74] Due to capacity limitations in the standardsupply chains, some manufacturers are3D printing healthcare material such as nasal swabs and ventilator parts.[75][76] In one example, when an Italian hospital urgently required a ventilator valve, and the supplier was unable to deliver in the timescale required, a local startup received legal threats due to alleged patent infringement after reverse-engineering and printing the required hundred valves overnight.[77][78][79]
There is disagreement as to whetherCOVID-19 has become anendemic disease or should still be considered apandemic. This transition has made COVID-19 data more difficult to track.[80] The observed behavior ofSARS-CoV-2, the virus that causes COVID-19, suggests it is unlikely it will die out, and the lack of aCOVID-19 vaccine that provides long-lasting immunity against infection means it cannot immediately beeradicated;[81] thus, transition to an endemic phase was probable. In an endemic phase, people continue to become infected and ill, but in relatively stable numbers.[81] Such a transition was thought to take years or decades.[82] Precisely what would constitute an endemic phase is contested.[83]
Endemic is a frequently misunderstood and misused word outside the realm ofepidemiology.Endemic does not meanmild, or that COVID-19 must become a less hazardous disease. The severity of endemic disease would be dependent on various factors, including the evolution of the virus, population immunity, and vaccine development and rollout.[82][84][85]
COVID-19 endemicity is distinct from the COVID-19public health emergency of international concern, which was ended by theWorld Health Organization on 5 May 2023.[86] Some politicians and commentators have conflated what they termedendemic COVID-19 with the lifting of public health restrictions or a comforting return to pre-pandemic normality.
As of 2024, experts were in disagreement as to whether COVID-19 had yet become endemic.[87][88][89] The transition point of a pandemic into an endemic state is not well-defined, and whether this has occurred differs according to the definitions used.[90]A key issue for epidemiologists is helping policy makers decide the main objectives of mitigation—e.g. minimising morbidity and associated mortality, avoiding an epidemic peak that overwhelms health-care services, keeping the effects on the economy within manageable levels, and flattening the epidemic curve to wait for vaccine development and manufacture on scale and antiviral drug therapies.
In the absence of eradication, the virus will likely become endemic, a process that could take years to decades. We will be able to establish that endemic persistence has been reached if the virus shows repeatable patterns in prevalence year on year, for example, regular seasonal fluctuations and no out-of-season peaks. The form this endemic persistence will take remains to be determined, and the eventual infection prevalence and disease burden will depend on the rate of emergence of antigenically distinct lineages, our ability to roll out and update vaccines, and the future trajectory of virulence (Fig. 4c)....Meanwhile, focusing on the epidemiology of the pathogen, it is important to bear in mind that the transition from a pandemic to future endemic existence of SARS-CoV-2 is likely to be long and erratic, rather than a short and distinct switch, and that endemic SARS-CoV-2 is by far not a synonym for safe infections, mild COVID-19 or a low population mortality and morbidity burden.