Much like pregnancy tests, they can produce results in about 15 minutes.
However, the tests require an uncomfortable nasal swab and are not as accurate as the molecular, or PCR, tests.
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They generally produce more "false negatives" which could mean sick people could slip through the cracks and onto planes.
An increasing number are hitting the market, from companies such as Abbott Laboratories, Becton Dickinson & Co and Quidel Corp and Roche, which is rebranding antigen tests from South Korea's privately held SD Biosensor.
Airlines are pressing governments to embrace alternatives to blanket travel restrictions amid a resurgence of Covid-19 cases in Europe.
Rapid antigen tests that can be administered by non-medical staff are expected to become available in coming weeks for as little as $7 each, the head of industry body the International Air Transport Association said on Tuesday.
Despite the drawbacks of such antigen tests, carriers hope they could tip the balance in convincing people to fly.
"It is to give ... confidence, at a specific point in time, that the result is positive or negative," said Christian Paulus, a Roche research and development manager.