‘Inaccurate but good for now’

PETALING JAYA: Non-contact infrared thermometers, also known as a “thermometer gun”, have become a familiar device when one enters any premises under the new norm since the Covid-19 outbreak.

But health experts warned that these thermometers could give off inaccurate temperature readings.

Universiti Malaya Department of Social and Preventive Medicine Faculty of Medicine Prof Dr Moy Foong Ming said detecting fever required measuring the body’s core temperature.

She explained that detecting a feverish person via oral digital thermometers were the most accurate, followed by ear thermometers but acknowledged that these thermometers were not practical for mass screenings.

“Thermal cameras and infrared thermometers are the next best alternatives,” she added.

Dr Moy explained that even if infrared thermometers could detect fever reliably, it could not prevent the spread of the coronavirus.

“Patients with Covid-19 may not have a fever (asymptomatic) and patients in the incubation period (which lasts two weeks) without any symptoms, including fever, may be infectious (pre-symptomatic).

“Passing the temperature check can create a false sense of security,” she said.

However, Dr Moy said temperature screenings might deter Covid-19 patients, especially those with fever, to conceal their illness. She said this would eliminate infections from symptomatic patients.

Dr Moy believed that maintaining social distancing, using hand sanitiser or washing hands, as well as wearing a face mask were still the “fundamental preventive measures for Covid-19”.

Universiti Malaya virologist Prof Dr Sazaly Abu Bakar concurred. “These are still the most effective ways of preventing Covid-19.

“Temperature scanning is just for the sake of going through the process. Most of the temperature screeners, the equipment itself, are not calibrated properly.

“I have my own personal experience of someone taking my temperature and it was 34 degrees. I should be in the hospital then!”

According to the US Food and Drug Administration (FDA), non-contact infrared thermometer measures a person’s surface temperature. It noted that these thermometer reduces “cross-contamination risk and minimises the risk of spreading a disease” but added that the close distance required to properly take a person’s temperature also represents a risk of spreading the disease.

The limitations to these thermometers, according to the US FDA, is that how and where it is used will affect the readings.

Dr Sazaly added that inaccurate readings and the use of poor thermometer equipment “defeat the purpose” of properly detecting those who were sick.

“Fever is also not necessarily reflective of a symptom of Covid-19, especially on those who are asymptomatic.

“It is better if there is a better machine; at least we can pick up those with not just Covid-19 but also those with dengue or other types of infections. The key is getting the right equipment that is properly calibrated,” he said.

Dr Sazaly said there were now new generation of scanners to detect people’s temperature such as those that were plastered to a door. “These do not require manpower to man the equipment and these were perhaps better equipment.”

At a press conference yesterday, Health director-general Datuk Dr Noor Hisham Abdullah said that temperature checks done at business premises would detect those who were symptomatic.

However, he noted that the infectivity of asymptomatic carriers were probably “very low” but clarified that the infectivity on presymptomatic was “very high”.

As such, he said his department would carry out active contact tracing on exposed individuals.

“We are then able to look at their close contacts to isolate them as soon as possible. If we are able to isolate them as soon as possible, we can prevent them from infecting other people,” he said.

Of the total 8,674 positive cases detected as of July 7, Dr Noor Hisham said 70.25% were asymptomatic cases while 29.75% showed symptoms.