DEC 24, 2021 8:59 PM PST

COVID-19 Tests & What to do About a Positive Result

WRITTEN BY: Carmen Leitch

There are several types of tests for COVID-19. A laboratory test for SARS-CoV-2 (the virus that causes COVID-19) can tell a person if they are currently infected, but may take a few days to complete. These can be PCR based, which can detect viral RNA that is present in a sample from a person's nose or mouth.. Some lab tests are Nucleic Acid Amplification Tests (NAATs), which also detect viral genetic material. There are several types of NAATS, which might be done in a lab, or may provide a result rapidly.

Rapid tests may also be antigen-based. Antigens can interact with a viral protein that is present on viral particles in a person's nose or mouth. When the antigen in the test links up with the viral protein, a color change may occur, for example.

Colorized scanning electron micrograph of a cell infected with a variant strain of SARS-CoV-2 virus particles, isolated from a patient sample. Image captured at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. Credit: NIAID

The CDC has tools to help determine if you need a test on the webpage linked here. Symptoms of COVID-19 still include fever, cough, difficulty breathing, fatigue, new loss of taste or smell, and other ailments listed here (the list is not exhaustivem they note).

The Food and Drug Administration has information about how the Omicron variant, now dominating spread in the United States and many other countries, impacts various tests. Some are still reliable while others are not; the FDA outlines which tests fall into those categories on their webpage. FDA-approved antigen tests are listed at this webpage.

Antibody tests for COVID-19 only determine if a person has been infected at some time. Vaccinations can also trigger positive results for some of these tests. Antibody testing is not recommended for people who want to know if they are currently infected.

The CDC is recommending that anyone, regardless of vaccination status, get tested for COVID-19 if they have symptoms of COVID-19, or they have been in close contact with someone who has the infection.

People who do not have symptoms but who were exposed are advised to isolate at home for fourteen days after their exposure, unless they are vaccinated. Those who are fully vaccinated do not need to isolate at home, however, it seems that most people who are symptomatic or who have been exposed should take as many precautions as possible until they get a negative result.

People who are fully vaccinated should wait five to seven days after their last exposure to COVID-19 to take a COVID-19 test, but those who are unvaccinated should take a test right away, and test again if they get symptoms or in five to seven days if their first test is negative and they have not developed symptoms. Anyone who has been referred by a workplace or other institution should also be tested.

If a person tests positive and does not have symptoms, the CDC states that the individual should isolate at home and away from other people, for at least five days (that recommendation is updated as of 12/27/2021). If people have symptoms, and their illness is mild, it's advised that they stay at home in isolation for at least five days after the symptoms improve. Those who are more likely to have a severe case are cautioned to contact their health care provider to advise them of their infection as soon as possible.

If people test negative but have symptoms, the CDC notes that they may have gotten a false negative result, so they should contact a healthcare provider for advice on how long to isolate.

Preventive measures can dramatically reduce the risk of COVID-19, including wearing a mask, and getting vaccinated. Learn more.

Sourxes: Centers for Disease Control and Prevention (CDC)

About the Author
Bachelor's (BA/BS/Other)
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
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