By Joanna Frank
As we recalibrate to a “new normal” in the midst of the COVID-19 pandemic, businesses and building owners are grappling with how to reopen safely. Eager to get back to work, they are looking for ways to ensure the physical well-being of occupants and employees, while also building confidence among those who may be hesitant to return. Many are considering fever screening as one way to improve both the physical and psychological well-being of occupants and visitors returning to commercial buildings. This raises the question – how effective is fever screening at detecting COVID-19?
Fever is a potential symptom of the COVID-19; however, it is essential to note that not everyone who has the virus exhibits symptoms. Because of this, it is likely that a large portion of those who are infected will go undetected. Screening as a means of preventing the spread of infectious diseases is, indeed, a sound public health concept. However, a false sense of security provided by fever screening has the potential to erode trust over the long run. In order to effectively mobilize fever screening strategies, we must consider the efficacy of entry temperature screening as a practice, as well as its role in building community trust.
Understanding Perceptions Of Risk
Perception of risk and levels of trust are interrelated. Research indicates that when individuals perceive a risk, they are slow to trust. Fever screening could be useful in providing confidence to building occupants and visitors, but because the evidence around COVID-19 is continuing to evolve, it will be important to also take a comprehensive approach by implementing evidence-based design and operational strategies—such as installing educational signage about hand washing and social distancing, increasing frequency of cleaning protocols, and improving ventilation. Given the known prevalence of asymptomatic COVID-19 cases, there is a real possibility that fever screening alone will not be effective in reducing risk, and this could ultimately cause occupants to lose trust in building owners, facility managers, or employers if transmission does occur in the workplace.
The disruptions and uncertainty brought by COVID-19 have a significant impact on our mental health. We saw similar trends in the wake of SARS, reinforcing the point that employers and building owners must pay close attention to mental health and well-being. Perception of risk and levels of trust will become more evident once commercial buildings reopen. In times of uncertainty, the perception of risk is high.1 One study found that during these times of uncertainty, people may use trust to assess risk.2
Building owners, facility mangers, and employers can help create environments that reduce perceived risks in order to help occupants feel safe and to trust the environment. Implementing fever screening at entry points may help to increase perceptions of safety, sending a message to occupants that the building is invested in their health and safety. This may also make individuals perceive the space inside as less risky. However, a low risk perception is likely to diminish the use of individual preventive measures, meaning that without comprehensive information on a multi-pronged approach to managing COVID-19 risks, a high-tech solution such as fever screening may create a false sense of confidence and result in individuals diminishing their vigilance around other effective preventive measures, such as hand washing.3
Findings From Recent Fever Screening Research
A preliminary review of the research indicates that fever screening on its own will likely miss a significant portion of the population in identifying COVID-19 infections. The efficacy of fever screening largely depends on the implementation, and the evidence suggests that fever screening is most useful as part of an integrated approach when followed by screening for other risk factors, such as a health questionnaire and diagnostic testing.4 Evidence from previous outbreaks indicates that fever screening has demonstrated little success in identifying infected individuals and limiting viral transmission. While the technology may identify a fever, unless it is part of a comprehensive screening strategy and point-of-care diagnostic testing for infection, it is largely ineffective. This is because of limitations of the existing technology, the characteristics of the virus itself, and variability in human behavior.
A study of the SARS prevention strategy at the Singapore Airport cites temperature screening conducted via thermal scanners as a vital component, but notes the successful identification of infected individuals was low.5 Meanwhile, another analysis concluded that “entry screening at airports is unlikely to prevent the importation of either SARS or influenza.”6 As one of the many countries impacted by SARS, Singapore provides one model to look to as we move through the next phase of COVID-19 pandemic. In response to COVID-19, Singapore has implemented mass fever screening by installing thermal temperature scanners at entryways to public buildings such as offices, hotels, community centers, and places of worship.7
Unlike SARS, which was most infectious when patients were critically ill, COVID-19 can be spread more frequently by asymptomatic individuals, making it more difficult to control and reducing the impact of temperature screening.8 The World Health Organization (WHO) emphasizes that temperature screening alone at travel points of entry may not be effective, as it could miss those who are asymptomatic.9 The WHO also notes that if temperature screening is implemented, it should be done so with other screening methods, such as health messages, questionnaires, and data collection and analysis, as well as a plan for how to proceed when suspected cases are detected.10
In addition, individuals may be symptomatic, but not febrile (showing symptoms of a fever). The likelihood a symptomatic person has a fever varies by pathogen. Fever is a non-specific symptom, especially in diseases like COVID-19 where symptoms are often delayed due to a longer incubation period, or the period between exposure to an infection and the appearance of the first symptoms. Fever detection can be useful in screening for individuals infected with viruses that have short incubation periods.11
Evidence has shown that syndromic screening at airports is only effective if the rate of subclinical (or asymptomatic) cases is negligible,12 which is not the case with COVID-19. COVID-19 appears to have a higher rate of subclinical infections than SARS and H1N1. One analysis of the Diamond Princess cruise ship found that 30.8% of those infected were asymptomatic.13 The CDC’s current estimate is that 35% of COVID-19 infections are asymptomatic.
Pitfalls Of Fever Screening
Temperature screening has the potential to be a part of comprehensive screening alongside a policy or protocol for what to do with those who do have a fever, such as follow-up care, testing, and hospitalization.14,15 Within an airport setting, researchers reported that even under “best-case assumptions,” screenings would miss more than half of infected travelers.16 Some inherent pitfalls around fever screening include:
False sense of security. Because the efficacy of fever screening is questionable, the implementation of this technology could give occupants a false sense of security. Emboldened with this confidence, occupants may be less vigilant about effective health measures, such as social distancing or wearing PPE. Thermal screening is not to be interpreted as a medical or clinical screening. It is not intended to diagnose, but rather to minimize risk of COVID-19 transmission. Building owners and facilities managers should be careful not to make claims that science and evidence cannot support, as this could build a false sense of security. There are much more effective measures, like social distancing and hand washing, which have an evidence-based impact on preventing the spread of the disease.
Privacy concerns. The ACLU is warning against the use of fever screening for these reasons, as well as stressing concerns about potential privacy issues around physiological surveillance and data collection. It’s also important to consider the potential stigmatization that could result from these practices for those who are perceived as a “risk.” If fever screening is implemented, people should always be given the option to leave rather than go through a public screening.
Technological limitations. While contactless, external temperature screening devices are helpful in that they limit physical contact, noncontact technologies such as infrared screening devices measure surface temperature, and may not reflect internal body temperature. Surface temperature is not always reliable as there are number of factors other than an infection that could cause a high reading, such as a sunburn, hot flashes, or having been in a hot environment. It is also possible that people could evade the technology by using fever-reducing medications, such as ibuprofen. There was a recent case of a worker at a meatpacking plant who died after taking Tylenol to reduce her temperature so that she could go to work. The current evidence on fever screening underscores the point that the percentage of asymptomatic cases of COVID-19 remains a crucial unknown, which significantly impacts screening effectiveness.17 Several studies have found that the reliability of technologies may be inaccurate. If the technology cannot do what it is intended to do, it should not be implemented. These are screening devices, not medical devices, and fever screening is not the equivalent to screening for a virus.
In summary, fever screening at entry points may help build confidence among office tenants, but it is not necessarily effective in reducing transmission risk. Fever screening is best implemented as part of a comprehensive infectious disease mitigation protocol, which may enhance perceptions of safety and help people to feel more confident about entering a facility or space. However, fever screening alone is not an infallible means of screening people who may be infected with COVID-19, and is not an effective preventive measure.
Notes
1 Siegrist, M. (2019). Trust and Risk Perception: A Critical Review of the Literature. Risk Analysis.
2 Siegrist, M., & Cvetkovich, G. (2000). Perception of hazards: The role of social trust and knowledge. Risk Analysis, 20(5), 713–719.
3 Aerts, C., Revilla, M., Duval, L., Paaijmans, K., Chandrabose, J., Cox, H., & Sicuri, E. (2020). Understanding the role of disease knowledge and risk perception in shaping preventive behavior for selected vector-borne diseases in Guyana. PLoS neglected tropical diseases, 14(4), e0008149.
4 Bitar, D., Goubar, A., & Desenclos, J. C. (2009). International travels and fever screening during epidemics: a literature review on the effectiveness and potential use of non-contact infrared thermometers. Eurosurveillance, 14(6), 19115.
5 Pitman, R. J., et al. (2005). Entry screening for severe acute respiratory syndrome (SARS) or influenza: policy evaluation. BMJ 331(7527), 1242-1243.
6 Tan, C. C. (2006). SARS in Singapore-key lessons from an epidemic. Annals-Academy of Medicine Singapore, 35(5), 345.
7 Lee, V. J., Chiew, C. J., & Khong, W. X. (2020). Interrupting transmission of COVID-19: lessons from containment efforts in Singapore. Journal of Travel Medicine.
8 Lum, L. H. W., & Tambyah, P. A. (2020). Outbreak of COVID-19–an urgent need for good science to silence our fears?. Singapore Medical Journal, 61(2), 55.
9 World Health Organization Updated WHO advice for international traffic in relation to the outbreak of the novel coronavirus 2019-nCoV. [February 20, 2020];2020d
10 World Health Organization Updated WHO advice for international traffic in relation to the outbreak of the novel coronavirus 2019-nCoV. [February 20, 2020];2020d
11 Gostic, K. M., Kucharski, A. J., & Lloyd-Smith, J. O. (2015). Effectiveness of traveller screening for emerging pathogens is shaped by epidemiology and natural history of infection. Elife, 4.
12 Quilty, B. J., et al. (2020). Effectiveness of airport screening at detecting travellers infected with novel coronavirus (2019-nCoV). Eurosurveillance, 25(5), 2000080.
13 Nishiura, H., et al. (2020). Estimation of the asymptomatic ratio of novel coronavirus infections (COVID-19). medRxiv.
14 World Health Organization. (2020). Updated WHO advice for international traffic in relation to the outbreak of the novel coronavirus 2019-nCoV.
15 Bitar, D., Goubar, A., & Desenclos, J. C. (2009). International travels and fever screening during epidemics: a literature review on the effectiveness and potential use of non-contact infrared thermometers. Eurosurveillance, 14(6), 19115.
16 Gostic, K., Gomez, et al. (2020). Estimated effectiveness of symptom and risk screening to prevent the spread of COVID-19. Elife, 9.
17 Gostic, K., et al. (2020). Estimated effectiveness of symptom and risk screening to prevent the spread of COVID-19. Elife, 9.
Joanna Frank is the founding President & CEO of the Center for Active Design (the sole license operator of the Fitwel Certification), where she advances design and development practices to foster healthy and engaged communities.
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