Can antigen testing replace nucleic acid testing for travel?

Sep 21, 2022 Source: Cainiu Health

Dr. Guo Xiheng

Introduction

Under normal circumstances, antigen testing cannot replace nucleic acid testing for diagnosis. Antigen tests may produce false-positive results, whereas the likelihood of false positives with nucleic acid testing is much lower. Nucleic acid testing is therefore considered an important and primary method for definitively diagnosing novel coronavirus infection. Thus, antigen testing cannot substitute for nucleic acid testing. When an antigen test result is positive, it is recommended to confirm the result with a nucleic acid test.

Antigen testing refers to the detection of antigens for novel coronavirus infection, while nucleic acid testing refers to the detection of SARS-CoV-2 nucleic acids. Generally, antigen testing for novel coronavirus infection cannot replace nucleic acid testing for travel purposes, as it may lead to false-positive results.

Novel coronavirus antigen testing detects the presence of viral antigens through an antigen-antibody reaction on a test strip, whereas nucleic acid testing examines specimens collected from a patient's respiratory tract to determine whether the virus’s genetic material is present, thereby confirming a diagnosis of novel coronavirus infection. Under normal circumstances, antigen testing should not be used in place of nucleic acid testing for travel, because antigen-antibody reactions in antigen tests may produce false-positive results due to potential interferences. In contrast, nucleic acid testing has a lower rate of false positives and higher accuracy. Therefore, antigen testing cannot replace nucleic acid testing. If an antigen test result is positive, it is recommended to confirm the result with a nucleic acid test for novel coronavirus infection.

It is important to note that individuals planning to travel should take proper personal protective measures, undergo nucleic acid testing at a正规 medical facility, wear masks correctly when going out, and practice timely disinfection. If the test result is positive, travel plans should be postponed, the case should be reported promptly, and the individual should isolate at home until a subsequent nucleic acid test confirms a negative result before resuming travel.

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How long does it take to test for influenza A and B virus antigens?

The reporting time for influenza A and B tests varies depending on the type of test—antigen, antibody, or nucleic acid (RNA) detection—but all three types can produce results within 2 hours. Influenza A virus and influenza B virus are both types of the influenza virus. Typically, after infection with the influenza virus, there is a certain window period before detection.

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How to perform an antigen test

Antigen testing generally involves washing hands thoroughly, collecting a sample, and performing the test. The test must be conducted strictly according to the instructions, as detailed below: Wash your hands before opening the antigen test package, and carefully check whether the packaging and contents are intact and undamaged, and whether they are within the expiration date. Tilt your head slightly backward, hold the end of the nasal swab, and insert it into one side of the nostril.