[colarris (OP)]

When this first became a major issue I saw news footage of officials in China holding some kind of small device in the faces random members of the public to test for infection. What device was they using and what exactly were they looking at?

[Bored chemist]

Could be a thermometer, or a political publicity stunt.
Or, give this, it could be a colourimeter.
http://www.rfi.fr/en/international/20200411-africans-targeted-in-southern-china-s-second-largest-city-as-covid-19-spreads

[chiralSPO]

I think they were infrared thermometers looking for people with fevers. A cheap and quick test that identifies people in need of more testing (many causes of fever), or at least greater extent of isolation/restriction based on being more likely to be infected/infectious.

[Bored chemist]

... and, given that most people are infections for a considerable time before they are ill, measuring temperatures is a pretty unreliable measure.
Unfortunately it may be the best we can do at the moment.

[colarris (OP)]

Appreciate the replies.