One of the essential steps in treating COVID-19 and stopping the spread of the disease is widespread testing to determine who has been infected. While widespread testing in the U.S. has lagged for a variety of reasons, the good news is that diagnostic procedures have been established, and many labs and companies are working on developing faster testing methods.
Currently, the most common coronavirus testing method is through a process called reverse-transcriptase polymerase chain reaction (RT-PCR).
When an individual gets tested for COVID-19, a healthcare worker swabs their nose or throat to collect a sample of mucus. This sample is placed in a vial, and shipped to a laboratory for testing. Keeping samples at the right temperature (between 35 and 40 degrees Fahrenheit), and shipping them fast enough (they must be processed within four days, or be frozen or discarded) are critical to ensuring the integrity of the specimen. Otherwise, samples may return inaccurate results.
In the lab, the first step is to extract the RNA, using substances called reagents. Enzymes are then added to complete the reverse-transcriptase process, through which the RNA is turned into DNA. Technicians add more reagents that copy the DNA, as well as fluorescent dyes that indicate the presence of the SARS-CoV-2 virus. The sample goes through a process of heating and cooling, known as polymerase chain reaction, in a special PCR machine. A light-measuring instrument in the PCR machine reads the fluorescent patterns in the sample, which indicates whether the sample does or does not contain the virus.
Generally, the RT-PCR process takes a few hours to complete, although the Food and Drug Administration (FDA) recently approved a new method that will show positive results in five minutes, and negative results in 13 minutes. This method, which uses a platform called ID NOW, will also allow for samples to be tested on-site, rather than being sent to a lab.
The most common method of sample collection has been a nasopharyngeal swab, in which a long Q-tip-like swab is inserted deep into the nasal passage. However, the FDA is now allowing individuals to use short swabs to collect samples from the front of their nostrils. Samples can also be collected from an individual’s throat.
If a patient has a productive cough, healthcare workers can collect a sample of phlegm to be tested, as the Centers for Disease Control and Prevention (CDC) recommends testing lower respiratory tract specimens when available. The CDC also recommends collecting a sample from the lower respiratory tract if the patient is receiving invasive mechanical respiration. It is currently thought that the virus reproduces in the respiratory tract, so samples collected directly from a patient’s lungs may contain more evidence of the virus. The CDC does not recommend inducing phlegm to get a sample.
As SARS-CoV-2 is a new strain of coronavirus, labs are developing other methods of testing to help fight the disease.
A number of companies have been working to create at-home COVID-19 tests, which would be useful for individuals who are under stay-at-home orders. This would also provide relief to healthcare workers, who may lack the gear necessary to protect them from individuals carrying the disease.
At-home tests would allow individuals to collect their own samples, through nasal swabs, and mail or deliver them to labs for testing. However, the FDA has not yet authorized the distribution or use of any at-home tests, citing concerns about false negatives stemming from incorrectly collected and shipped samples.
Read more: At-home COVID-19 Testing
Many individuals who have been infected with COVID-19 have only displayed mild symptoms, or been completely asymptomatic, and therefore were never tested for the disease. To get a clearer picture of how many total people have been infected, the CDC is also working to develop a serology test. These types of tests use blood samples to detect antibodies, which are proteins made in response to infections. If a person has these antibodies in their system, it means they were infected with COVID-19, even if they never became seriously ill or displayed symptoms.
Knowing exactly who has had COVID-19 will help public health experts understand how widespread the disease is, and may help them develop treatments and vaccines.
Currently, individuals are being tested for COVID-19 at the discretion of state and local health departments, and individual clinicians, due to limited supplies of test kits, testing materials, and protective gear for healthcare workers.
The Association of Public Health Laboratories recommends prioritizing testing for certain groups, including healthcare workers and first responders with COVID-19 symptoms; older individuals with COVID-19 symptoms, especially those who live in group settings like nursing homes, and individuals with other illnesses whose treatment might change if they have COVID-19.
Individuals experiencing any of the following symptoms of severe illness should seek medical attention and testing immediately:
If you are experiencing minor COVID-19 symptoms and are not over 65 or immunocompromised, you should contact your healthcare provider. They will determine if you need to be tested for COVID-19. Your healthcare provider can also provide guidance for treating your symptoms with over-the-counter medications, and self-isolating if necessary.
Read more: When to Get Tested for Coronavirus
|Centers for Disease Control and Prevention (CDC)||https://www.cdc.gov/coronavirus/2019-ncov/index.html||The CDC is the United States’ leading national public health organization. Its mission is to protect public health and safety through the control and prevention of disease, injury, and disability in the U.S. and abroad.|
|World Health Organization (WHO)||https://www.who.int/||A specialized agency of the United Nations, WHO is responsible for international public health. Headquartered in Geneva, Switzerland, it has field offices worldwide.|
|Association of Public Health Laboratories (APHL)||www.aphl.org||The APHL is a nonprofit organization in the United States that represents laboratories that protect public health and safety.|
|State Departments of Health||https://www.fsis.usda.gov/wps/wcm/connect/fsis-content/internet/main/topics/recalls-and-public-health-alerts/additional-recall-links/state-departments-of-public-health/ct_index||Each state in the U.S. has its own department of health. These public health departments are currently coordinating efforts for COVID-19 testing and treatment.|