Coronavirus: US approves new antigen test with fast results

US regulators have approved a new type of coronavirus test that administration officials have promoted as a key to opening up the country.

The Food and Drug Administration on Saturday announced emergency authorisation for antigen tests developed by Quidel Corporation of San Diego. The test can rapidly detect fragments of virus proteins in samples collected from swabs swiped inside the nasal cavity, the FDA said in a statement.

The antigen test is the third type of test to be authorised by the FDA.

Currently, the only way to diagnose active COVID-19 is to test a patient’s nasal swab for the genetic material of the virus. While considered highly accurate, the tests can take hours and require expensive, specialised equipment mainly found at commercial labs, hospitals or universities.

A second type looks in the blood for antibodies, the proteins produced by the body days or weeks after fighting an infection. Such tests are helpful for researchers to understand how far a disease has spread within a community, but they aren’t useful for diagnosing active infections.

Antigen tests can diagnose active infections by detecting the earliest toxic traces of the virus rather than genetic code of the virus itself.