The expansion of testing is an important element in balancing prevention of the spread of the novel coronavirus and social and economic activities. However, can coronavirus antibody testing, which shows if a person has been previously infected, be used to confirm whether people are "safe" from the virus?
There are two methods to determine whether a person is currently infected with the virus: PCR (polymerase chain reaction) testing and antigen testing. PCR tests are used to determine the existence of the virus gene, and antigen tests check for the existence of a virus-specific protein.
In contrast, antibody tests can only determine the existence of certain antibodies in the blood. Antibodies are made by the immune system, which works to protect the body from harmful external substances such as viruses. The antibody test will show if a person has had specific infections even if they were asymptomatic. Given this, the Health, Labor and Welfare Ministry conducted antibody tests on about 8,000 people aiming to grasp the actual state of infection.
Antibody testing is an effective way to survey the spread of infection, however, it is not suitable to determine the current infection situation.
"There are some cases where people will test negative for the antibodies because not enough time has passed after they were infected and the antibodies have yet to be formed, or because the level of antibodies in the blood is too low for the test to detect," said Hidekazu Nishimura, director of Virus Research Center at the National Hospital Organization Sendai Medical Center.
However, experts are concerned that there is a widespread misconception that antibody testing can be used to prove safety. More and more medical institutions are accepting requests for antibody testing as part of a health checkup because all it requires is a blood sample.
Some theater plays, concerts and other event organizers tout that the events are safe because antibody testing has been conducted. However, when a mass infection was confirmed at a theater in Shinjuku Ward, Tokyo, in July, one of the performers who did not feel well performed at the theater because he had tested negative in an antibody test.
Also, even if a person carries coronavirus antibodies, it cannot be said that he or she will not become infected again. Some countries considered lifting restrictions on going out by issuing an "immunity certificate" to those who tested positive for the antibodies, but the World Health Organization asked them to refrain from issuing such certificates, claiming there was no evidence to prove a positive result of an antibody test justifies the lifting of the restriction.
The accuracy of the tests must also be taken into account. A study by the Japanese Association for Infectious Diseases found that the accuracy of the tests varies among manufacturers of test kits and reagents. As research progresses, it may become possible for the tests to be used more effectively, but, at the moment, it can be said that taking the test as an individual is not very beneficial.
Read more from The Japan News at https://japannews.yomiuri.co.jp/
