This week, US authorities announced that they would only allow passengers to have a PCR or Antigen test for flights to the US. Find out which test is and what it is for.
What is the antigen test?
The antigen test is used to detect if a patient has COVID-19. In general, if you test positive, it means that you currently have COVID-19 and can pass the virus to other people.
How does the test work?
Antigen tests look for specific proteins, called “antigens,” of the SARS-CoV-2 virus. If the test shows these antigens, it means that the person has the virus in the body.
How long do the results take?
Results can be ready after as little as 15 minutes or up to an hour.
When is the antigen test used?
Antigen tests are used in people who have symptoms of COVID-19.
These tests are quick and less expensive than PCR. Used properly, they can help prevent the spread of COVID-19 in places where people live together, such as schools, nursing homes, or prisons.
How are the tests done?
Generally, a healthcare provider inserts a swab into the nose. Sometimes the provider may ask the patient to insert the swab into the nose to collect the sample himself.
Where can an antigen test be done?
Some healthcare facilities can do an antigen test. Ask your healthcare provider or clinic who can do it, or check with your local health department.
When does a person test positive?
Antigen tests work best within the first seven days of symptoms. After that period, the test could be negative, even if a person has the virus.
If you have symptoms but have a negative test result, you may need to have a PCR test to confirm the result. If necessary, your healthcare provider will recommend it.
How accurate are the tests?
Antigen tests are generally very good at detecting the virus but not as good as PCR tests. Generally, if you have symptoms and the test indicates that you have COVID-19, you have the virus.
However, the test can wrongly indicate that you have COVID-19 even if you don’t have it (false positive). If that happens, your healthcare provider might ask you to have a PCR test to know for sure if you have COVID-19.
We still don’t know how effective antigen tests are at detecting the virus in people who have no symptoms.