This is a test: Understanding the various types of COVID testing

Yuma Regional Medical Center uses the Polymerase Chain Reaction (PCR) test to identify SARS-CoV-2, the virus that causes COVID-19. This test uses a respiratory nasal swab to collect a sample from suspected COVID-19 patients.

COVID-19 is such a new disease that experts still have much to learn about how it spreads. A lot of the confusion among the general public centers on testing and, in particular, who may need testing and how to get tested.

The Yuma Sun spoke with Dr. Bharat Magu, chief medical officer at Yuma Regional Medical Center, for information on the kind of testing available to the public.

TYPES OF TESTING

There are two types of tests available, but each serves a different purpose. Since the beginning of the pandemic, the healthcare system has mostly relied on one kind of test to diagnose COVID-19: the polymerase chain reaction test, better known by its acronym PCR.

The PCR test can identify SARS-CoV-2, the virus that causes COVID-19. This test uses a swab to collect a sample from the back of a patient’s nose or throat. Results come back in about 48 hours or, if tested on a weekend, about 72 hours.

More recently, there has been news about antibody testing, which is different than the diagnostic test. With the antibody test, also called serology testing, a blood sample is taken and analyzed to determine if someone has potentially been infected in the past. Antibodies are “ little tiny proteins that the body produces in response to any foreign infection in the body.

“It’s almost like a reflection of the virus. It detects exposure in the past,” Magu explained.

The hope is that antibody testing will help researchers better understand how widespread the virus is. “What this will give is a rough estimate of the prevalence of the exposure in the community,” Magu noted.

However, both tests have advantages and disadvantages, Magu said. With PCR, he noted, if the infection is low and there are not enough viruses in the nose or throat, the test might come back falsely negative. 

“They still have the bug, but the PCR test is much more likely to be negative,” Magu said.

The antibody test takes a while to become positive. Even if a person has had symptoms for several days, the body might not have produced enough antibodies to come out positive. This is why the antibody test is not good for diagnosing the virus.

WHO NEEDS TESTING

Not everyone who develops symptoms of fever, cough, shortness of breath and difficulty breathing will need to be tested. YRMC is still mostly using the PCR test in high-risk patients and employees, and now that elective surgeries restart on Monday, the hospital is also testing patients scheduled for surgery.

A person’s healthcare provider determines whether a patient should be tested for COVID-19 based on the symptoms, as well as whether the patient has had close contact with someone diagnosed with COVID-19, or traveled to or lived in any areas with ongoing community spread in the past 14 days.

The healthcare provider also may consider testing if a patient is at higher risk of serious illness, especially if the person has an immunocompromised system or heart disease.

YRMC will start antibody testing high-risk employees over the next couple weeks to determine the percentage of exposure and help the hospital make decisions.

RAMPING UP

At this point, YRMC is testing between 30-40 high-risk patients a day. As of 9 a.m. Friday, YRMC had tested 627 patients, of which 55 came back positive, 501 negative, and 71 pending. 

A few patients have been retested, and they have been positive. Therefore, the total number of positive tests does not equate to the total number of positive patients.

“These numbers change throughout the day,” Magu said, adding “I wish we could open a lot more testing.”

Testing will see a significant jump in the next few weeks when YRMC joins the “blitz” testing effort announced by Gov. Doug Ducey. The hospital, in partnership with the City of Yuma, will hold its first drive-thru testing on Saturday, May 9, from 8 a.m. to 12 p.m., at the Yuma Civic Center.

Then YRMC will start looking at testing more patients in collaboration with the University of Arizona over the next three months.

The number of antibody testing depends on the capacity of the Mayo Clinic, which processes the YRMC samples. The hospital is also looking at using an in-house lab for the PCR tests but is awaiting approval from the FDA. 

“It appears we are close to getting the approval of the FDA. We are hopeful,” Magu said.

The hospital hopes to ramp up testing, but it’s limited to the supply of test kits on hand.

“We always need more,” Magu said. “As of now, we are stable. Maybe a couple of weeks’ worth of stock on hand.”

Employees are constantly trying to find more test kits, but they are high in demand, short in supply. “The microbiology department, as soon as they come in every day, they start making phone calls,” Magu said.

“We try to source them from wherever we can. Sometimes we get lucky, we get a stock of 200, and then we wait another two weeks before we get some,” he added.

He noted that testing is also available at other outside labs, including LabCorp, Sonora Quest, Marine Corps Air Station and some community providers. Sunset Health is also holding drive-thru testing beginning today and the next two Saturdays.

Magu noted that with COVID-19 being so new, there are still things that aren’t known about the virus. It’s important to continue to follow the guidelines to prevent the continued spread of COVID-19, including proper hand-washing, not touching your face, maintaining social distancing, and avoiding outings and gatherings.

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