COVID-19 tests are conducted in commercial, private and academic labs, as well as state and county health labs, and are also available for at-home use. UC Davis Health has greatly expanded our on-site testing capabilities, having developed and validated our own accurate COVID-19 test.

COVID-19 testingThe most accurate COVID-19 test, a molecular PCR test, involves inserting a 6-inch long swab (like a long Q-tip) into the cavity between the nose and mouth (nasopharyngeal swab) for 15 seconds and rotating it several times. The swabbing is then repeated on the other side of the nose to make sure enough material is collected. The swab is then inserted into a container and sent to a lab for testing.

Your health care provider can best advise you about the need to be tested for COVID-19. Testing is encouraged if you are experiencing COVID-19 symptoms or have been exposed to someone who testsed positive for the virus.

Health experts caution that COVID-19 tests only tell you what your staus is for that exact moment in time. For example, you could have been exposed to the virus a few hours before testing but haven't reached the level that can be detected by a COVID-19 test.

View a list of COVID-19 symptoms you should watch for

Find a COVID-19 testing site in California near you

You can find a COVID-19 testing location near you through the state of California's COVID-19 website.

You can view individual county testing resources as well:

UC Davis Health patients and non-patients with COVID-19 symptoms can contact a doctor through UC Davis Express Care or by contacting your primary care provider by phone or MyUCDavisHealth. A doctor can help quickly coordinate a COVID-19 test, possibly at a UC Davis Health drive-up site in Sacramento, which are available seven days a week.

Access UC Davis Express Care for patients

Access UC Davis Express Care for non-patients

Healthy Yolo Together, a public health project of UC Davis, also provides free saliva-based COVID-19 testing at locations in Yolo County.

Read more from UC Davis Health: More options than ever for at-home and community COVID-19 tests

[ + LARGE VIEW ]

A diagnostic test, known as a molecular PCR test, uses a nasal swab and collects samples of cells and fluids from your respiratory system. It enables the identification of specific genes for the SARS-CoV-2 virus that causes COVID-19. The specimen is collected using a long nasal swab that is inserted into the passageway between the nose and the back of the throat. PCR tests, like the ones used by UC Davis Health's lab, are close to 100% accurate in diagnosing COVID-19 infection, but the disadvantage is they take a little more time for results.

Rapid antigen tests account for most of the rapid diagnostic tests. These are done with a nasal or throat swab and looks for a protein that’s part of the virus. Antigen tests are less expensive and have a generally quicker turnaround time, sometimes within 15 mins. However, they are less accurate because if a person is not near peak infection, but still contagious, the tests may come back negative. The CDC advises people who show COVID-19 symptoms but test positive with an antigen test to get a PCR test to confirm results.

An antibody test, also known as a serology test, is done with a blood sample that may identify past infection of the virus that causes COVID-19. It’s a test that looks for evidence of the body’s immune response to the virus. Antibodies are detected in the blood after an infection. However, with COVID-19, we don’t fully know what the presence of its antibodies means yet.

Learn more about the different types of COVID-19 testing

To determine which test you should take, know why you're being tested.

Rapid antigen tests are now being used at schools for rapid screening. They are good for this purpose. Or maybe your child has been exposed at school, and after quarantining per the CDC guidelines, they need to have two negatives tests. So, the parents may want to buy a rapid antigen home kit.

But in other instances, a molecular PCR test is more appropriate. A PCR test can be used for asymptomatic testing or to confirm a positive antigen test. It's also used when patients are experiencing symptoms, need to be tested before a procedure, or when they are being admitted to the hospital. PCR tests are often used to make clinical decisions.

With all home-use tests on the market, whether antigen or PCR, following testing instructions is very important to ensure the quality of testing. For example, if a swab isn’t inserted deep enough into the nose, it may not collect a good sample for testing and may give a false negative.

Read more from UC Davis Health: More options than ever for at-home and community COVID-19 tests

COVID-19 tests are free at testing sites. If you're insured, you can get a COVID-19 test from your health provider or any out-of-network provider. If you don't have insurance, the government pays for your test.

Asymptomatic testing means getting tested when you don’t have any COVID-19 symptoms and don’t feel sick. Although it might seem pointless to get tested when you are fine, asymptomatic testing has been a key strategy in tackling the pandemic. It can identify people who may be carrying the COVID-19 virus and are spreading it but don’t know they’re infected. Most asymptomatic people develop symptoms later on.

Especially if you are unvaccinated, you should be tested for COVID-19 even if you're asymptomatic. Additionally, asymptomatic testing is required for unvaccinated people in certain workplaces, including at any University of California (UC) campus, and to attend certain events, like concerts and sporting events.

Even if you are vaccinated against COVID-19, experts still recommends asymptomatic testing. As of early September, about 25% of positive cases are in people who are vaccinated.

There are over-the-counter PCR testing kits for at-home use. You can purchase them online, take the test, and mail it in. Results come back in about 48 hours. Amazon even has their own PCR test that provides results within 24 hours of their lab receiving it.

Read more from UC Davis Health: More options than ever for at-home and community COVID-19 tests

Rapid antigen tests search for protein pieces from the virus and are known to be less sensitive than molecular PCR tests. These COVID tests perform best with people in the early stages of COVID-19 infection, when viral load is the highest.

No test is completely accurate, which means that some cases will be missed (false negatives) and some people will be told they have the virus when they don’t (false positives). Positive tests tend to be accurate, but negative tests need to be interpreted with caution, especially in a high-risk setting or when used on asymptomatic people.

Rapid antigen tests are best used as intended, where a person tests at least twice over a 36- to 48-hour period to increase the odds of detecting an infection.

View the FDA's list of over-the-counter antigen tests that have been authorized for emergency-use authorization

Learn more about COVID rapid tests

UC Davis Health has rolled out a groundbreaking, highly accurate test that can check for both COVID-19 and flu viruses at the same time, returning results in 20 minutes. We are the first in the region and among the first in the nation to use these rapid, combined molecular tests at the point of care.

For now, the combined COVID-19 and flu tests will be limited to the emergency department or situations when speed is critical to understand a patient’s condition. Fast, accurate flu and COVID-19 results can help with management and treatment of both viruses. They can also eliminate hours or sometimes days of anxiety for patients.

Read more about the rapid test for flu and COVID-19

Learn more about COVID rapid testing

[ + LARGE VIEW ]

Yes. Our clinical laboratory began internal testing in March, 2020, using CDC assays (tests to determine the presence of infectious agents like COVID-19).

At the same time, we developed high-throughput assays on the Roche Diagnostics cobas® 6800 System to meet an expected surge in cases. The commercial device has the capacity to perform more than 1,000 tests per day.

We don’t really know what the presence of COVID-19 antibodies means. It doesn’t necessarily mean that you’re immune to the virus. Medical science has yet to determine what level of antibodies confirm immunity, if immunity is possible, or how long immunity might last. The result of a positive antibody test indicates past infection and/or immunization, but may not correlate with immunity.