Covid-19: The thermal scanners being used may be offering false hope

Thermal scanners are able to pick out anybody who has a fever at the time of the scan. However, it takes an average of five days (two to 14 days, in some cases 21 days) from the time of infection to when symptoms start. PHOTO | NATION MEDIA GROUP

What you need to know:

  • Even a precise temperature sensor would not necessarily catch everyone carrying the Coronavirus.
  • Infected people can take several days to develop a fever and other symptoms.
  • According to the Centers for Disease Control and Prevention, as many as 25 percent of people with Covid-19 have no tell-tale signs.

Operating a business while keeping staff safe from Covid-19 is a tough field to plough. Employers are duty-bound to protect their staff. Screening staff for fever before entering an office is one of the widely used practices to identify feverish staff — but the thermal scanners being used may be offering false hope.

Thermal scanners are equipped with an infrared sensor that can immediately tell if someone has a fever, potentially presaging Covid-19. The scanners take the temperature of the surface of the body without contacting a person's skin.

Most thermal imaging screening devices will flag that someone has a fever if their body temperature is over average, between 37 and 38 degrees Celsius.

While the gadgets can sense elevated skin temperatures, public health officials warn, they can be wildly off the mark in telling whether someone has a fever or something else. The warmth of a person's skin is often quite different from their core body heat.

The distance between the thermal scanner and the skin matters: If those wielding the scanners do not hold them close enough to a person's forehead, they generate lower than the actual temperature. If they hold the device too close, they get an erroneously higher temperature. Overweight or people with current health problems or hot flashes can trigger the thermal scanner's alarm.

The measurements can also be imprecise if temperature scanning is done in dusty environments as dust forms a thin film on someone's skin, leading to an inaccurate reading.

The scanner may miss someone who has taken medication to suppress a fever.

The devices could also inadvertently expose employees who are running higher temperatures because they are under duress, an issue that some workers may prefer to keep private.

Staff with elevated body temperature for whatever reason would ideally be sent home or referred for further tests, a situation that can trigger suspicion about one's health, which may not bode well with staff.

 Even a precise temperature sensor would not necessarily catch everyone carrying the Coronavirus. Infected people can take several days to develop a fever and other symptoms. According to the Centers for Disease Control and Prevention, as many as 25 percent of people with Covid-19 have no tell-tale signs.

There are also concerns that many of the worker-screening tools are being introduced with minimal government oversight. For instance, there must be clear guidance on how organizations use or safeguard their staff health data, or how long they plan to keep it.

Here is my point: As employers confront the uncharted Covid-19 waters, they must balance between the health of their business and their workers' health.

Thermal scanners are essential tools in risk mitigation, but their shortcomings must be reviewed and addressed. Importantly, governments must lead with guidelines on the appropriate type of thermal scanners, how to use them and how to safeguard staff privacy.

Mr Wambugu is an informatician. Email: [email protected] Twitter: @samwambugu2