Can thermal scanners pick up Covid-19?

Thermal scanners are effective in detecting people who have a fever but cannot detect those who are infected with Covid-19, the World Health Organisation says.

The WHO said the scanner, used by many establishments and in workplaces,  is a helpful tool in the fight against Covid-19 by picking up a higher than normal body temperature that may point to symptoms of the virus.

It, however, noted there are many causes of fever and one should call a healthcare professional if one has concerns. This is especially important in areas where malaria or dengue is widespread.

The National Institute for Communicable Diseases (NICD) said those who may have contracted malaria may struggle to differentiate between it and Covid-19 as they have similar symptoms. 

These symptoms include: fever, chills, fatigue, headache, and muscle and joint pain. 

Symptoms of Covid-19 typically develop within five days after infection but can show as early as two days or as late as 10 days after infection. Conversely, malaria symptoms start showing 10 days after infection. A person may feel ill as soon as seven days after infection or as late as a year later.

Covid-19 symptoms include cough, loss of taste and smell and sore throat, while early malaria symptoms typically include fever, chills and headaches.

Prof Cheryl Cohen, co-head of the centre for respiratory disease and meningitis at the NICD, said thermal scanners can be used to pick up possible Covid-19 infection early, but warned that they are not 100% effective.

“So if a person happens to have a fever and we test them and isolate them from society, then this is a helpful part of our defence against the virus,” she said. She added thermal scanners cannot pick up the virus if someone is in the incubation period between exposure to Covid-19 and showing symptoms.

“A person in the incubation period will have the virus in their body but there is no sign that they are sick, they don’t have a fever and they can go on to get sick later. So these people can never be picked up by thermal scanners or any other screening tests,” she said.