Coronavirus: Blood test looks for antibodies to determine if you are infected even if you don't show symptoms
The test developed by scientists in the US can also tell whether people who recover from the infection stay immune to the virus
US scientists have developed a blood test capable of detecting the body's weapons -- antibodies -- against the new coronavirus to determine if you are infected or have fought the disease in the past.
These tests can help scientists uncover some of the mysteries behind the virus. It can tell whether a person has encountered and fought off the virus. It can also tell whether people who recover from the infection stay immune to the virus.
With these tests, "labs could screen a few thousand people a day for antibodies against the new coronavirus," study senior author Florian Krammer, a virologist at the Icahn School of Medicine at Mount Sinai in New York, told Science magazine. What is more, other labs can also develop these tests by following the procedure detailed in the preprint study.
Currently, Krammer told Science that he has deployed these tests in a New York Hospital to understand the duration of people's immunity against the virus.
How are these tests different from the usual tests?
Currently, health workers collect nasal or throat swabs. In them, they look for the virus's genes: its presence indicates that a person is positive for the virus.
Antibody tests, on the other hand, provide more detailed information. It is especially useful to catch the virus in people who show no symptoms. Emerging evidence suggests that people with mild or little symptoms are driving the pandemic. These people often go undetected as they are usually not tested.
A recent study predicted that 86% of the infected people --who may have had mild or no symptoms -- in China went undetected. The scientists believe that this group may have passed on the infection to two-thirds of the population that was infected.
Similarly, another study drew similar conclusions. "At least 59% of the infected individuals were out and about, without being tested and potentially infecting others. This may explain why the virus spread so quickly in Hubei and is now circulating the world," lead author Wu Changchun, from Huazhong University of Science and Technology in Wuhan, wrote in the study.
Antibody tests can provide conclusive proof as it can map out the extent of coronavirus infections in a region.
How do antibodies accomplish this?
To understand if our bodies have fought off the infection, scientists look for antibodies. If the antibodies are present in our blood for extended periods, scientists can conclude that we can still ward off a second infection. But the virus is new and we do not know how long the antibodies last and hence antibody tests have generated a lot of interest.
The antibody test detects our body's natural weapons against invaders called antibodies. "Now, typically, when we get infected with a virus, we make antibodies, especially against proteins on the surface of the virus," Dr. Krammer tweeted. These antibodies, in turn, recognize the spike and destroy the virus if it were to attack again.
The team then identified the viral protein that instigates the immune system: spike protein. Krammer and his team developed a version of the spike. The antibodies in an individual's blood, for instance, can specifically attach to the spike, more like how a lock binds to a key.
With this test, we can figure out who was infected and who wasn't, Krammer wrote in a tweet. It could help in treatment too. Recovered patients can donate their blood and it can be used to treat other patients, he explained.
"Please keep in mind that these conclusions are preliminary and based on small numbers. Larger studies to confirm these are needed and ongoing," he tweeted.