COVID-19 has impacted organisations in a variety of ways. We were in the midst of a 7-day worksite visit when Australian case numbers surged in March and observed the rapid evolution of strategies to protect workers. Strategies include a voluntary declaration of travel history and acute symptoms, hand and respiratory hygiene, distancing of workers on-site, working from home for non-essential staff, additional cleaning of communal worksite facilities and increasingly, temperature screening of workers on entry to site. Temperature screening is presumably utilised due to fever being the most frequently reported symptom of the coronavirus (Tian et al., 2020). As detailed in our latest paper (Daanen et al., 2020), fever is defined as a core body temperature of >38ºC, but screening based upon core temperature is not a viable option for worksites given its invasive nature and logistics required. Hence, temperature measurement of the skin is utilised as a surrogate for core temperature. Essentially, temperature screening is relying on heat radiating from the skins surface to be representative of core body temperature, and that the measuring device accurately detects temperature of the skin. Given the range of factors that influence skin temperature (including ambient conditions) and accuracy issues of detection devices, the efficacy of temperature screening for the coronavirus is questionable. In fact, based upon a review of temperature screening for Severe Acute Respiratory Syndrome (SARS), Influenza Pandemic (H1N1) and Ebola Virus Disease, the authors reported that this method was ineffective (Mouchtauri et al., 2019). Effectiveness is determined by the ability to detect positive cases, which in turn is dependant upon the threshold temperature utilised. Choose too high a temperature and you're unlikely to detect any cases. Choose a temperature too low and you risk false-positives which may require invasive temperature measurement for confirmation. And remember that fever is not present for all coronavirus patients.
With these issues in mind, why is temperature screening utilised in airports, medical clinics and worksites (see image below). Irrespective of the ability to detect fever, temperature screening may have positive effects through raising awareness, education and discouraging movement of potentially infected persons (Mouchtauri et al., 2019). Additionally, in the pursuit of improving workforce health and safety, temperature screening provides organisations with a tangible strategy that is observed by workers. Lastly, workplace temperature screening kits and screening services are marketed as per this example, reinforcing the apparent suitability for organisational use.
An example of temperature screening prior to worksite entry. (Photo - Forbes Advocate).
For sites with a large workforce, thermal imaging has emerged as an option to negate one-by-one assessment but again, this method is not supported by evidence. In fact, the Medicines and Healthcare products Regulatory Agency (MHRA) (UK) states "Many thermal cameras and temperature screening products were originally designed for non-medical purposes, such as for building or site security. Businesses and organisations need to know that using these products for temperature screening could put people’s health at risk". Read the full article here.
In response to the MHRA article, Prof. George Havenith, Director of the Environmental Ergonomics Research Centre at Loughborough University summed up why skin temperature assessment and thermal imaging should not be relied upon for worksite screening (Twitter, July 4, 2020):
In summary, we urge employers not to rely on temperature screening to solely determine if a worker has a fever, and therefore, more likely to be infected with the coronavirus. A range of strategies are required to protect workers from the coronavirus, with the ability of medical personnel to interact with workers, albeit from a distance, a key benefit of temperature screenings as opposed to the assessment of temperature per se.
Daanen H, Bose-O'Reilly S, Brearley M, Flouris A, Gerrett N, Huynen M, Jones H, Lee JKW, Morris N, Norton I, Nybo L, Oppermann E, Shumake-Guillemot J, Van den Haze P. COVID-19 and thermoregulation-related problems: Practical recommendations. Temperature. In press.
Mouchtouri VA, Christoforidou EP, An der Heiden M, Menel Lemos C, Fanos M, Rexroth U, Grote U, Belfroid E, Swaan C, Hadjichristodoulou C. Exit and Entry Screening Practices for Infectious Diseases among Travelers at Points of Entry: Looking for Evidence on Public Health Impact. Int J Environ Res Public Health. 2019;16(23):4638.
Tian S, Hu N, Lou J, et al. Characteristics of COVID-19 600 infection in Beijing. J Infect. 2020;80(4):401–406.