Coronavirus Testing

Coronaviruses are a large group of viruses that can cause illness in animals and humans. Some coronaviruses commonly circulate in the United States and usually cause upper respiratory symptoms such as cough or runny nose, although some can cause more serious illness. The 2019 novel (new) coronavirus causes the illness coronavirus disease 2019 (COVID-19).

The symptoms

People with COVID-19 have had a wide range of symptoms reported – ranging from mild symptoms to severe illness. Symptoms may appear 2-14 days after exposure to the virus. People with these symptoms may have COVID-19:

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

Older adults and people who have severe underlying medical conditions like heart or lung disease or diabetes seem to be at higher risk for developing more serious complications from COVID-19 illness.

Testing

Learn more about the different types of tests and the steps involved.

Types of Tests

There are two different types of tests – diagnostic tests and antibody tests.

1. A diagnostic tests can show if you have an active coronavirus infection and should take steps to quarantine or isolate yourself from others. Currently there are two types of diagnostic tests which detect the virus – molecular tests, such as RT-PCR tests, that detect the virus’s genetic material, and antigen tests that detect specific proteins on the surface of the virus.

2. An antibody test looks for antibodies that are made by your immune system in response to a threat, such as a specific virus. Antibodies can help fight infections. Antibodies can take several days or weeks to develop after you have an infection and may stay in your blood for several weeks or more after recovery. Because of this, antibody tests should not be used to diagnose an active coronavirus infection. At this time researchers do not know if the presence of antibodies means that you are immune to the coronavirus in the future.

There are some new diagnostic tests available with alternative methods and benefits.

• Rapid, point-of-care diagnostic tests use a mucus sample from the nose or throat but can be analyzed at the doctor’s office or clinic where the sample is collected and results may be available in minutes. These may be molecular or antigen tests.
• At-home collection tests, available only by prescription from a doctor, allow the patient to collect the sample at home and send it directly to the lab for analysis.
• Saliva tests allow a patient to spit into a tube rather than get their nose or throat swabbed. Saliva tests may be more comfortable for some people and may be safer for health care workers who can be farther away during the sample collection.

Molecular Tests

Many companies and labs have developed tests to diagnose COVID-19 based on detection of the virus’s genetic material in a sample from the patient’s nose or throat. These steps may change as new technology becomes available, but currently the typical steps in molecular testing are:

1. A doctor, pharmacist, or other health professional orders a COVID-19 test. All COVID-19 tests, including those used with a home collection kit, require a prescription or order from a health professional.
2. You or a healthcare professional use a specialized swab to collect mucus from your nose or throat.
3. You or a healthcare professional put the swab in a sterile container and seal it for transport to a lab.
4. During the shipping process, most molecular test swabs must be kept within a certain temperature range so that the test will be accurate. The sample must arrive at the lab within 72 hours.
5. A lab technician mixes chemicals with the swab to extract the genetic material of any virus that may be on the swab.
6. The lab technician uses special chemicals, called primers and probes, and a high-tech machine to conduct several controlled heating and cooling cycles to convert the virus’s RNA into DNA, and then make millions of copies of the DNA. Some tests use only one warming cycle to make copies of the DNA.
7. When DNA binds to specific probes, a special type of light is produced that can be seen by the machine and the test shows a “positive” result for infection with SARS-CoV-2, the virus that causes COVID-19.

Molecular diagnostic tests that detect the genetic material of the virus are commonly used for diagnosing COVID-19 or active coronavirus infection. But no test is 100% accurate all of the time. Some things that may affect the test’s accuracy include:

• You may have the virus, but the swab might not collect it from your nose or throat.
• The swab or mucus sample may be accidentally contaminated by the virus during collection or analysis.
• The nasal or throat swab may not be kept at the correct temperature before it can be analyzed.
• The chemicals used to extract the virus genetic material and make copies of the virus DNA may not work correctly.

Antigen Tests

Antigen tests usually provide results diagnosing an active coronavirus infection faster than molecular tests, but antigen tests have a higher chance of missing an active infection. If an antigen test shows a negative result indicating that you do not have an active coronavirus infection, your health care provider may order a molecular test to confirm the result.

Antibody (Serology) Tests

Antibody tests may provide quick results, but should not be used to diagnose an active infection. Antibody tests only detect antibodies the immune system develops in response to the virus, not the virus itself. It can take days to several weeks to develop enough antibodies to be detected in a test.

Coronavirus Testing In Your Community

The best way to get a coronavirus test is to contact your health care provider. You may also visit your state or local health department’s website to look for the latest local information on testing.