The Infectious Disease Association of Thailand has pointed out that the antigen test is at its most useful when given to those who have been exposed to COVID-19 and have begun to show symptoms.
Association chairman Dr. Kamthorn Malatham said the antigen test, which detects protein chains, is of particular value when taken two days before symptoms show and in the week following the first signs of infection. The antigen test can also produce a false negative if there are low virus loads.
He said, however, that any early diagnosis can reduce the severity of symptoms by ensuring people get timely treatment, as well as helping to stop them from spreading the disease unwittingly.
Dr. Kamthorn also urged those with known exposure, but with no symptoms, to bear in mind that the tests can still produce false results and to act in a hygienic and conscientious manner, adding that antigen test results are less accurate when used by those with no symptoms. (NNT)