Selected and edited by Rafaela Prifti/
The latest news briefings on coronavirus claim that wide-testing for antibodies needs to be conducted in order to allow lifting of restrictive measures and opening the country for business. The antibody tests that evaluate whether one has been infected with the coronavirus are on their way, according to officials. As governments around the world would come to rely on the serology tests for safely opening the economic sectors, the scientific community evaluates the accuracy of the serology tests. The UK government has ordered 3.5 million home test kits to allow Britons to conduct antibody tests at home that could transform UK’s response to Covid-19.
The return to the work place or public gatherings for many Americans could depend on an antibody test, which is a blood test that determines whether someone has ever been infected with the coronavirus.
Those who appear to be immune may be able to safely return to work. It is particularly important to test the health care workers who could continue to provide care for sick people. The Centers for Disease Control and Prevention recently announced that it would begin using antibody tests to see what proportion of the population has already been infected. On Friday, the National Institutes of Health announced it would test 10,000 healthy volunteers around the country for the presence of antibodies.
“Within a period of a week or so, we are going to have a relatively large number of tests available,” Dr. Anthony S. Fauci, the leading infectious disease expert in the U.S. In the latest White House news briefing, Dr. Fauci said that the idea of “certificates of immunity” is being discussed. One major consideration in opening the country is understanding “how much that virus has penetrated society.” Immunity certificates have some merit under certain circumstances,” he said. The idea of providing proof of immunity to allow workers to return to their jobs is being considered in many countries, including Britain and Italy.
What Is a Serology Test?
Antibody identification involve analyzing a patient’s sample (usually blood) for the presence or absence of a particular antibody or for the amount of antibody that is present. Antibodies are part of the body’s immune system. They are immunoglobulin proteins that help protect people against microscopic invaders such as viruses, bacteria, chemicals, or toxins.
A serology test looks for signs of an immune response — in this case, to the new coronavirus. When your body encounters a virus, it takes some time for it to recognize the invader and to begin to scale up an immune response. Immune molecules called antibodies are a crucial part of this response.
The first type of antibody to appear is called immunoglobulin M or IgM and its levels spike within a few days of infection. But IgM is a generic fighter. To target and destroy a specific virus, the body refines it into a second type of antibody, called immunoglobulin G, or IgG, that can recognize that virus. As IgG levels rise, IgM levels drop; IgG levels peak around 28 days after the onset of infection. There is a third type of antibody, called IgA, present in mucosal tissues, like the inner lining of the lung. IgA is known to be important for fighting respiratory infections such as influenza, and is likely to be central in coronavirus infection, too. Many of the tests being developed look for levels of all three antibodies; some look for just IgM and IgG, and still others test for only one type.
The Antibodies Are One Piece of Immunity Response
Simply having antibodies is no guarantee of immunity. Antibodies are one piece of the complex immune response. The current tests are more effective at detecting the presence of antibody responses across large numbers of people which would reveal how widely the virus has spread in the population. These tests are not helpful for diagnosing an early infection.
The data shows that 25 to 50 percent of people who become infected may never develop symptoms, and some may become only mildly ill. A percentage who were sick and could not get tested due to limited testing availability would be identified. Serology tests would help scientists to estimate the infection rate before the data started to be recorded and also determine with more accuracy the death rate of Covid-19, the disease caused by the virus. Tracking the rise and fall of antibody levels may also enable scientists to back-calculate the dates of infection, and help them predict whether the virus shows seasonal fluctuations.
For the governments that have seen the county’s economy grind to a halt, the serology tests can reveal which people are protected from re-infection and can safely go back to work. Understanding the full scope of the pandemic could be the decisive factor for ending social isolation measures and allowing businesses to reopen.
Most of the current tests being developed offer a simple yes-no answer to the question of who has antibodies, and who was exposed to the virus. In the cases of people who had mild or no symptoms, for example, they might have developed antibodies that are too weak to prevent re-infection. Conversely, others who have low levels of IgG may still be protected. That’s because antibodies are just one well-understood piece of the immune response. Immune cells called T-cells may also be involved. In other tests, plasma from people who have strong antibodies is being used to treat people who are unable to mount an immune response.
When Will Serology Tests Be Widely Available?
Last month, the F.D.A. allowed developers to begin to sell or use antibody tests without first getting the agency’s permission, once the companies had done their own evaluations to ensure the tests were accurate and reliable. Since then, more than 70 test developers have notified the agency that they have serological tests available. But the agency said some companies have falsely claimed that their tests were F.D.A.-approved, or falsely claimed they could diagnose Covid-19. The C.D.C.’s project is one of dozens. The World Health Organization is also planning to test large numbers of people in multiple countries. Some universities, townships and countries have begun testing on their own.
Some tests are already available and being used, yet it is early and unclear how accurate they are. Last week, the Food and Drug Administration granted an emergency use authorization to one such test. But others are being used in research projects and by hospitals. Many issues have already surfaced.
In the U.K., for example, the tests are plagued with false negatives – not picking up antibodies when they are present – and with false positives – indicating antibodies when there are none. Some of the tests may not be specific enough to the new coronavirus; they may pick up a signal from antibodies made in response to infections with the coronaviruses that cause common colds. False positives, in particular, are dangerous because they can lull people into believing they are immune when they are not, and becoming exposed to the virus.
How Long Does Immunity To Coronavirus Last?
Since it is a new virus, the scientific community does not estimate exactly how long immunity to the virus will last. By comparing it with the common cold coronaviruses, as well as the more dangerous ones that caused SARS and MERS, they state that immunity to these viruses persists anywhere from one to eight years. According to them, the studies that are needed will have to follow people who have contracted the virus and other who have not. That will take time.