A guide to COVID-19 tests: When to test, what kind to use and how to use the results

Jan. 17—EAU CLAIRE — As COVID-19 cases surge in the Chippewa Valley and across the nation amid the spread of the highly contagious omicron variant, testing is considered a key to identifying people who need to isolate to protect others. That means COVID-19 tests are in high demand. Here are answers to some frequently asked questions about testing:

What is the difference between a PCR and an antigen test?

Polymerase chain reaction, or PCR, tests look for the virus' RNA in a patient's sample, which is usually collected by inserting a swab into a person's nostril. PCR tests are the most accurate for determining if you have the coronavirus and thus are considered the gold standard when it comes to COVID-19 testing, according to Mayo Clinic.

Depending on the lab your provider uses, you generally can expect to receive your results within 24 to 72 hours.

Antigen tests, also called rapid tests, detect a viral protein in the nasal sample and can produce results in 15 minutes. These tests, given with a nasal swab, may not be as accurate, especially for people who are not showing symptoms. However, a positive test is considered a probable case of COVID-19.

Both types of tests can be performed at a health care provider, community testing site or with an in-home kit.

When should I seek which type of test?

If you have symptoms of COVID-19, whether you are vaccinated or not, seek testing right away, advised Elizabeth Goodsitt, spokeswoman for the Wisconsin Department of Health Services. If you were a close contact of someone who has been diagnosed with COVID-19, you should be tested at least five days after exposure if you do not have any symptoms. You can choose whatever viral test you can most easily access. These include PCR tests or rapid antigen tests.

If you want to test before gathering with people from outside of your home, a rapid antigen test is recommended, Goodsitt said.

Where can I get tested?

A list of community testing sites in Eau Claire County can be found on the Eau Claire City-County Health Department website: https://bit.ly/33IPMhU.

A map of community testing sites in Wisconsin can be found on the DHS website: dhs.wisconsin.gov/covid-19/community-testing.htm.

Where can I find at-home rapid antigen tests in Wisconsin?

At-home rapid antigen tests can be found at pharmacies, grocery stores, discount stores, health care providers and online, but they can be difficult to find because of high demand.

Starting Wednesday, you can order a test from COVIDTests.gov, which the federal government will send out at no cost, including no shipping fees. A half-billion tests will be available for order at first, with an additional 500 million on order. To distribute the tests, the Biden administration will partner with the U.S. Postal Service.

The state of Wisconsin and Vault Medical Services have teamed up to provide at-home collection kits to everyone who lives in Wisconsin at no cost. Sample collection is supervised over a video call by a health care professional and therefore can be used to inform official public health decisions. Residents can request a free, supervised at-home collection kit here: dhs.wisconsin.gov/covid-19/collection.htm.

How should I use the results to guide my actions?

Knowing if you are infectious with COVID-19 can help you plan more effectively and make you feel safer when participating in certain social activities. If you test positive for COVID-19, you should isolate immediately, Goodsitt said. Self-tests are an important tool that can help reduce your chances of spreading COVID-19.

If you test positive using a self-test, you most likely have COVID-19 and should isolate immediately. If you test negative, you likely do not have COVID-19, but should follow the manufacturer's instructions regarding serial testing, which may recommend you test again within two or three days.

"At-home tests can provide information for individuals who want a rapid result of whether they have COVID and may be an option that they consider before gathering in groups for example," Dr. Ryan Westergaard, chief medical officer for DHS's Bureau of Communicable Diseases, said at a media briefing last week. "But when it comes to decisions about returning to work or returning to school, our recommendation is to not use at-home tests but use ones that are done in a supervised setting where we can be confident that the proper steps were followed and the interpretation is correct."

Can I use antigen or PCR test results to end isolation or get out of it early?

No, it is not possible to test out of isolation early, as someone who tested positive for COVID-19 or has symptoms should only get tested toward the end of their five-day isolation period, Goodsitt said. Here is the current U.S. Centers for Disease Control and Prevention testing guidance for symptomatic and asymptomatic cases:

—Isolation — symptomatic: If an individual has access to a test and wants to test, the best approach is to use an antigen test toward the end of the five-day isolation period. Collect the test sample only if you are fever-free for 24 hours without the use of fever-reducing medication and your other symptoms have improved (loss of taste and smell may persist for weeks or months after recovery and need not delay the end of isolation). If your test result is positive, you should continue to isolate until day 10. If your test result is negative, you can end isolation, but continue to wear a well-fitting mask around others at home and in public until day 10.

—Isolation — asymptomatic: If an individual has access to a test and wants to test, the best approach is to use an antigen test toward the end of the five-day isolation period. If your test result is positive, you should continue to isolate until day 10. If your test result is negative, you can end isolation, but continue to wear a well-fitting mask around others at home and in public until day 10.

What are the most frequent mistakes people make regarding testing?

"Testing too early after exposure," Goodsitt said. It is recommended that people wait to test until at least five days after last close contact with someone with COVID-19. People who are up to date with their COVID-19 vaccines or those who are exempt from quarantine should also get tested at least five days after close contact with someone with COVID-19.