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Temperature Screening Best Practice

Temperature Screening Best Practice
Temperature screening can be an effective mitigation method to help slow the spread of COVID-19 and other highly infectious respiratory diseases, if adequate technology and a suitable process are employed.

Sometimes referred to, incorrectly, as fever screening systems, monitoring for elevated skin temperatures can provide a frontline temperature triage to identify individuals that may be exhibiting a higher than expected temperature.

A high surface temperature can be a strong indicator of a fever, a symptom of COVID-19, and therefore a reason for a further check to verify if an individual has a feverish temperature with a calibrated, tympanic ‘in-ear’ medical thermometer.

While temperature screening can be effective, the requirements for the equipment used to obtain a reliable, repeatable, and accurate measurement are very specific, and many systems currently being marketed for this purpose are inaccurate and inadequate for this task.

To be clear: there are no thermal temperature screening systems available on the market today that are able to diagnose COVID-19. However, if correctly specified and installed, they can accurately detect temperatures above a specified range or threshold, such as 100.4 °F (38 °C) , the Center for Disease Control (CDC) definition of fever.

This guide is designed to help you distinguish between appropriate technology, and equipment that is inadequate for reliable human skin temperature measurement. 
It also contains advice about how to implement best practice protocols and how to avoid the common pitfalls in temperature screening.

The amount of energy radiated by the human body is relatively low. Therefore, external factors that can adversely influence the measurement of temperature need to be seriously considered to provide a suitable level  of accuracy. 

Rapidly changing ambient conditions, reflections, and sources of heat in the measurement area can all adversely affect the accuracy of the measurement.

To overcome many of these issues, the concept of ‘in-scene’ calibration utilizes a constant temperature reference source, commonly referred to as a Blackbody Source (BBS) that is in the same frame of measurement as the person being measured. 

Using this method, algorithms can be developed by the manufacturer that can ‘calibrate’ the reading in ‘real-time’ to provide greater assurance of accuracy with varying ambient conditions.

The incorporation of a BBS into a temperature screening system does not guarantee accuracy. If the location of the BBS is not standardised, the compensation algorithm may require 
a complex set-up and can therefore be subject to error. 

This source of error can be removed by integrating the BBS into the screening system, helping to produce reliable results 

To recognise the difference between good and bad practice, a further understanding of the benefits and limitations of the different types of technology that can be used for temperature screening is critical.

Government guidance, recommendations, and mandates have been issued in many regions, such as in the USA by the Food & Drug Administration (FDA) and CDC, to add temperature screening to the core countermeasures of social distancing, frequent hand hygiene, and the use of face coverings.
There are different methods of temperature screening, which all have varying levels of ease of use, accuracy, repeatability, and practicality.

For example, a rectal temperature reading is considered to give an accurate measurement of core body temperature. Whilst accurate, if taken with a sensitive and calibrated medical thermometer, it is impractical and far from ideal for encouraging staff, customers, or visitors back to a facility. 

Certified in-ear medical thermometers, again if calibrated, are also considered to give an accurate reading of body temperature. While more practical than the previous suggestion, this method also involves close contact. The use of this type of device is good for a final temperature check, but is not suitable to use in the main temperature screening process, as it increases close contact risk and will slow the movement of people considerably.