When and What Day to Test for COVID-19

If you have been around someone who has tested positive for COVID-19, you should get tested. It is the only way to know for sure whether you have the illness.

If you choose not to get tested, you may unknowingly pass the virus to others. You can even pass the virus before symptoms start and even if you are asymptomatic (have no symptoms). 

You have a couple of options for COVID-19 testing, including rapid tests for testing at home. No matter how you plan on testing, knowing the right time to take a COVID-19 test and which test to use can be challenging. 

This article covers when to test, types of available tests, test results, and more. 

When to Take a COVID Test  

When you test often depends on when you were exposed and whether you have symptoms.

Guidance for COVID-19 testing comes from the Centers for Disease Control and Prevention (CDC). It recommends waiting at least five full days after a known exposure to test. The CDC also recommends you self-isolate and test right away if you are experiencing COVID-19 symptoms. 

CDC guidance on when to test for COVID-19 includes:

• Test if you have COVID-19 symptoms.
• If you have symptoms and test negative for the COVID-19 virus, you can continue to test daily or test again at 48 hours.
• If you have been exposed to someone with a confirmed case and do not have symptoms, wait five days before testing. 

You should also test before attending a large event or visiting someone at high risk for infections or COVID-19 complications. You should test within 24 to 48 hours before the event or visit. 

Most people will test positive once they are showing symptoms. Symptoms of COVID include:

• New loss of taste or smell
• Fever or chills
• Sore throat
• Fatigue
• Congestion or runny nose
• Cough
• Nausea or vomiting
• Diarrhea
  
• Shortness of breath or breathing troubles
  
• Muscle and body aches
• Headache
  

A 2023 study found that when people are infected with SARS-CoV-2, the virus that leads to COVID-19, their viral load (amount of virus in the body) is the highest four to five days after symptoms start. According to the study's authors, testing too early could give you a false-negative result (testing negative even though you're positive) because of a lower viral load at this time. 

If you are feeling sick, you should test and seek medical care. If you are someone who is at high risk for COVID-19 complications or you have had severe symptoms in the past, you should seek antiviral treatment as soon as symptoms start.

You can also test positive if you have a COVID-19 infection without symptoms. One 2021 research review reported asymptomatic COVID-19 in 40.5% of people who tested positive for the virus.

Not having symptoms should not dissuade you from getting tested for COVID-19. If you avoid getting tested after exposure and truly have the disease, you could put others at risk, especially high-risk individuals.

Sore Throat and COVID-19

Having a sore throat or another lone symptom of COVID-19 does not mean you have COVID-19. A sore throat can be a symptom of other respiratory illnesses, including the common cold, the flu, and strep throat. Furthermore, not everyone with COVID-19 experiences a sore throat. 

While rare, it is possible to experience a sore throat as a lone symptom of COVID-19. In this case, your illness would be considered mild. Around 81% of people with COVID-19 report a mild or moderate illness.

If you are concerned your sore throat is related to COVID-19, you should get tested, especially if you have been around someone else who is sick or if COVID-19 numbers in your local community are high.

Types of COVID-19 Testing 

You can test for COVID-19 using an antigen test or a polymerase chain reaction (PCR) test. Both tests are good at detecting active infections.

Antigen tests are also called rapid tests and can be performed at home or in a clinic. PCR tests are analyzed in a lab, which may take a few days to get results. 

Rapid Test

As the name indicates, a rapid COVID test gives you fast results. These tests are simple to use and can be done in the privacy of your home. They can also be done at a healthcare provider's office or a COVID testing site. They do not need laboratory processing.

You can buy at-home rapid tests from a local pharmacy, grocery store, or online retailer without a prescription. You can test at home and get the tests within a short time.

Results of rapid tests are usually produced within 15 to 30 minutes. While a positive test can be accurate and reliable, rapid tests are less likely to detect the virus, especially in asymptomatic people. That means getting a negative test does not rule out infection.

PCR Test

According to the CDC, PCR tests are the gold standard for COVID testing. These highly sensitive tests are the most precise method for diagnosing an active infection. 

They are a type of nucleic acid amplification test (NAAT), which means they are more likely to detect the virus than a rapid antigen test.

Your healthcare provider will take a sample specimen from your nose or mouth for the PCR test. The sample is then sent to a laboratory for testing. It may take up to three days for results. 

Testing for COVID: Understanding Results 

If you take a rapid test at home, a positive result means you likely have COVID-19. You should contact a healthcare provider, who can recommend treatment options. You should also follow the CDC's guidelines for staying home and isolating to reduce the spread of the virus.

The CDC recommends isolating for at least five days if you test positive for COVID-19. You should start isolating as soon as you start having COVID-19 symptoms, even before testing positive for the disease.

According to a 2021 JAMA Internal Medicine report, you are most contagious in the first two days before and after symptoms start. You could be contagious up to 10 days after symptoms start, especially if you have a more severe disease.

A negative result from an at-home rapid test means the test did not detect the virus that causes COVID-19, but this does not rule out the infection. This is because some tests do not detect the virus early on, and you may not get a positive result until you develop symptoms. In this case, you will want to repeat the test. 

The Food and Drug Administration (FDA) recommends retesting after a negative result without having symptoms if you have been in close contact with someone who tested positive or if COVID-19 is active in your community.

If your PCR test was positive, the test detected the presence of SARS-CoV-2 in your nasal or oral secretions. This result means you are infected with COVID-19 and should self-isolate. If you are older or have high-risk health conditions, contact a healthcare provider to consider antiviral treatment.

If your illness is mild, you can recover at home without medical care, but you should contact a healthcare provider if symptoms get worse or you are having breathing troubles.

While rare, a false-positive result can occur (one that is positive, but you don't have the infection). This is because the virus has RNA (a type of nucleic acid found in all living cells) as its genetic material. PCR tests make many copies of the genetic material from the virus. A positive sample is unlikely when viral RNA is absent. Even so, a false positive could occur, often due to contamination, a lab mix-up, or human error. 

A negative PCR test means you likely did not have an active COVID-19 infection when the test was taken. This result could mean you do not have the virus, but it is also possible to get a false-negative result.

This results when an infected person has insufficient viral genetic material from the sample for the PCR test to detect the COVID-19 virus and the results show negative when they should be positive for an active infection. This may happen if you test too early after exposure. A false negative is more likely than a false positive.

When to Retest for COVID-19 

To be sure you do not have COVID-19, the FDA recommends two negative antigen (at-home, rapid) tests if you have symptoms and three negative tests if you do not to reduce the risk of spreading the infection. Tests should be separated by at least 48 hours.

A single PCR test can confirm a rapid test, and no further testing would be needed. If you develop symptoms days after receiving a negative PCR result, you might consider an at-home rapid test or contacting your healthcare provider for a second PCR test, especially if you have severe symptoms or you are at high-risk for infections or COVID-19 complications.

Summary 

COVID-19 testing is vital to the treatment and prevention of the virus. However, determining when to test and which test to use can be challenging. 

You should test when you experience symptoms of the infection and if you have been around someone who has tested positive. If you have symptoms, test right away. Wait five days to test after exposure if you do not have symptoms.

If you have symptoms but test negative, you should test again after 48 hours. You should also test within a day or two before a large event or a visit to someone considered high-risk for COVID-19.

Rapid antigen tests are the most widely available and can be done in the privacy and comfort of your home. Results are available in around 15 to 30 minutes. 

PCR tests are considered the gold standard for COVID-19 testing because they are highly sensitive and can detect viral genetic material. A PCR test is done in a healthcare setting and sent to a lab with results in a few days.

A positive test likely means you have the virus and should isolate at home to avoid spreading the infection. If you have symptoms and have not gotten a positive result, isolating is still a good idea. If you tested negative with a rapid home test, you should wait 48 hours before retesting. A third test is recommended for someone who doesn't have symptoms but has had an exposure and tests negative on the first two tests.