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The Ins and Outs of COVID-19 Testing. Who is being tested? What are tests looking for? When might we have a vaccine?

March 20, 2020
by Colin Poitras

Now that the new coronavirus known as SARS-CoV-2 has established a foothold in the United States, many communities are ramping up testing for infection. Yale School of Public Health Assistant Professor Amy Bei helps explain the testing and how officials are using the tests to monitor the spread of COVID-19, the disease caused by the virus. (Editor’s note: This information here was gathered on March 19. Some details provided may have changed. For the latest information, visit Connecticut’s coronavirus website.)

Who should be tested?

A.B.: Testing is currently recommended for people who have symptoms (such as a fever greater than or equal to 100°, cough, or difficulty breathing). If symptoms like these develop, call a doctor first and discuss with them the specific symptoms and also potential exposures, either with individuals known to be infected or if you live in a community where cases have been detected. Right now, testing is not recommended for individuals without symptoms. An order from a primary care physician is needed to be tested for COVID-19.

The following is an advisory from Connecticut health officials: If you do not have a primary care provider, and you have the symptoms of COVID-19, please go to an urgent care center or to a federally qualified health center to get a doctor’s order to be tested. Do not go to any medical facility unannounced for the safety of all patients and medical professionals. Drive-thru testing sites are present on hospital grounds.

If you are displaying symptoms consistent with those of COVID-19, and are unable to get into contact with your primary care physician, please reach out to one of the following hotlines:

  • Hartford Healthcare Hotline: (860) 972-8100
  • Yale New Haven Health: (833) 484-1200
  • Bristol Hospital Coronavirus Info Line: (860) 261-6855
  • Stamford Health: (203) 276-4111

Is there a cost for being tested?

A.B.: On March 18, a federal relief package aimed at helping individuals and families impacted by the COVID-19 pandemic was approved by Congress and signed into law. Under this legislation, testing for the coronavirus is free, including costs for visiting a doctor or an emergency room examination for diagnostic testing. Many private insurance companies are waiving testing costs for their members, but I would advise people to check with their providers first to be sure. Testing costs are also being covered by Medicare and Medicaid.

How are the tests conducted?

A.B.: The CDC recently updated its recommendations for sampling and is now prioritizing a sample from the upper respiratory tract, specifically a nasopharyngeal swab (a swab taken through the nose that collects a sample from the back of the nose and the throat). If oral swabs are taken, they should be combined with the nasal swab. The goal of these samples is to detect the virus in the upper respiratory tract.

What is the test measuring?

A.B: The CDC test is a nucleic acid-based test which means that it is detecting the viral RNA in these samples. The test is not a rapid “point of care” test that can be performed quickly at home or at a doctor’s office, thus it requires samples to be collected and shipped to labs with special equipment. The test uses a quantitative method of amplifying the viral nucleic acid in the sample to the point of being able to measure it. It usually takes about 24 hours from the time of sample collection to the final test result, but times can vary. The reason the test takes this long is that samples must be collected, stored at the right temperature, shipped to an appropriate authorized laboratory, the samples must be carefully treated, and run on a machine that can measure the amount of viral nucleic acid. Once the result is measured on the machine, the results can be communicated to the patient. A positive test means that there is virus in the respiratory tract of the person at the time of sampling. A negative test means that there is no virus in the person at the time of sampling, or that the amount of virus is too low to be amplified (which can occur if the sample is taken very early after the onset of infection, for example). If additional exposures occur, or if symptoms worsen, discuss with a physician to determine whether additional testing may be recommended.

Is the nasal swab test the only way to detect COVID19?

A.B.: There are actually two different kinds of tests, but right now, there is only one which is approved for use. This may change as other tests are in development and are seeking approval from the FDA. The nucleic acid test is used to diagnose patients with active disease. There is also an antibody test under development that is used to measure exposure to the virus (current exposure or past exposure). This test is not meant to necessarily identify active cases, although there are ways of determining this from these tests, but it is mainly used by epidemiologists for surveillance purposes, to try to understand the extent of exposure in a population, whether or not the population know they are infected or feel sick. The two tests have different goals and are used to measure different aspects of the disease: active symptomatic infection for diagnosis (nucleic acid test) and exposure (antibody test). This second kind of test measures antibodies, which are proteins generated by our immune responses to fight infectious diseases. Even after the infectious agent has been eliminated by the body, antibodies remain and can serve as markers of past exposure. These kinds of tests are especially useful in determining how many people in the population have been infected, especially if they have few or no symptoms. Antibody tests have been developed for past coronavirus outbreaks (SARS and MERS) but took significant amount of time and effort to develop as they relied on the correct animal models and validation with patient samples. These tests did indeed involve testing antibody responses to different proteins and running a second test to confirm a positive result. Classic antibody-based tests to measure exposure and rapid-antibody based tests for active infection with Covid-19 are currently under development.

When might we expect a vaccine to be made to help fight this virus?

A.B.: The process of making a vaccine has different steps, or phases. As you move through the phases, the number of volunteers required increases and the kind of information gathered changes. Scientists want to understand if the vaccine is safe, if it is able to activate an immune response, and finally – will it work, and can it protect people? Because safety is one the most important aspects of a vaccine trial, it takes time to proceed through the phases, in order to ensure that a vaccine approved for the general public is above all, safe and won’t harm anyone. In developing a new vaccine, it is important to proceed through each of these phases in order to find a vaccine that will protect everyone and is safe for all. This process usually takes at least a year or more before a new vaccine is proven clinically safe and effective. We know that scientists around the world in both the public and private sectors are working tirelessly to develop a vaccine for COVID19.

Learn more about Bei’s work.

Submitted by Denise Meyer on March 20, 2020