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What is serological testing?

  • Serological testing determines if someone is immune to the coronavirus
  • It requires a blood sample
  • It’s currently being developed by medical labs around the globe

One of the most important factors for how soon the United States can open back up from the coronavirus pandemic will rely heavily on widespread testing. Standard COVID-19 testing employs a method called PCR—or, polymerase chain reaction, widely used in molecular biology—which looks directly for the virus by using genetic material taken from a patient’s nasal or throat swab to determine if they are infected.

And while the importance of those tests can not be stressed enough, another test we tend to hear less about is serological testing—which is just as, if not more, important.

Unlike standard swab testing, serological testing requires blood samples, and instead of determining if an individual is infected with the virus, these tests determine if someone has previously been exposed to the virus. Serological tests look for the antibodies (or, lack of antibodies) which would be present in the blood of someone who has already contracted the disease and, therefore, has already built an immune response to the infection.

In other words, the test detects the body’s immune response to the infection caused by the virus, rather than detecting the virus itself.

These coronavirus antibody tests are currently being developed by a number of medical science labs around the world, including the researchers at the Icahn School of Medicine in New York City.

The Icahn team tests for antibodies by reproducing copies of the highly immunogenic “spike” protein on the virus’s surface. This spike is a telltale sign that an individual’s immune system sees the virus, so it can then start producing the necessary antibodies to fight it off.

The test works by exposing the blood sample to the spike protein. If the test lights up, it means that it is positive for antibodies.

How serological testing could help end the pandemic lockdown

The importance of this testing lies in that it can help determine (along with other clinical data) when people are no longer susceptible to infection and can return to work—particularly healthcare workers and others on the front lines. Additionally, it can help establish who may be eligible to donate a part of their blood called “convalescent plasma,” which has the potential to serve as a possible treatment for critically ill COVID-19 patients by helping boost their immunity.

Sneha Patel, CEO of Metroplex Medical Centres in Dallas, has already ordered thousands of these tests and will be offering drive-thru testing sites at multiple locations across the Dallas-Fort Worth metropolitan area in the coming weeks—with each site able to handle up to 400 tests per day.

“Other countries who are two or three weeks ahead of us, they’re even saying we should be testing more people who are without symptoms so that we can get a better handle on this and get people back to work,” Patel told WFAA in Dallas. Although, she admits, “Time is not on our side right now.”

Fortunately, serological testing is quick and easy. It requires only a single drop of blood from a finger prick and delivers results in just 15 minutes. If the results are positive, a line appears on the test, similar to a pregnancy test.

But it’s unclear if serological testing is working correctly.

In a report issued by Johns Hopkins Center For Health Security on April 22, the authors wrote, “While serology testing has the potential to provide valuable information to individuals and to public health authorities, there are significant areas of uncertainty that will need to be addressed in the coming weeks and months. The first and most urgent is serology test validation. There are dozens of serology tests being marketed in the United States that are not providing accurate information and that are not comparable to each other.”

On May 5, it was reported that a biotech company from Switzerland called Roche Holdings said it had developed a test that is 100% accurate at detecting the antibodies from the coronavirus. The FDA has given its approval, and Roche is expected to produce millions of tests this month.

Sources: FDA, MIT Technological Review, WFAA 8 News, Johns Hopkins


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