Testing negative on COVID-19 antibody tests does not mean approved for work

There have been reports of a COVID-19 outbreak in a theater in Shinjuku. According to the reports, one of the performers was not feeling well, but since they tested negative on a COVID-19 antibody test, they performed anyway. The antibody test helps decide whether someone is infected by checking how the body’s immune system reacts to the pathogen. It takes time to create antibodies after getting infected, so it is easy to get a false negative when someone is in the early stages of infection. Therefore, people should not take antibody tests as the only solid proof that they are negative for COVID-19.


　However, that is not always the case for infectious diseases. For example, antibody tests are usually used to determine if someone is infected with the Hepatitis C Virus (HCV). Although someone will contract acute hepatitis after being infected by HCV , dying with that alone is very rare. The primary concerns for Hepatitis C are: it can evolve from acute to chronic hepatitis; liver cells can slowly deteriorate and develop cirrhosis; and, liver cells can become cancerous.


　A usual test is conducted in order to find the cause of the symptoms. However, there are almost no symptoms for chronic hepatitis that can be confirmed through self-examination alone. For that reason, screening tests are conducted where people with no symptoms are tested and may be found positive with the virus. Screening tests are an easy and cost-effective way to test a large number of people.


　A PCR test can also be used to check for HCV, but for those who do not have the symptoms, the fee that comes with the PCR test can be quite expensive. With only the antibody test, lab technicians can find people who have a higher chance of being infected. If someone tests positive, they have to go through a more thorough examination and get a PCR test. People can still test positive on an antibody test after recovering from the virus, but a thorough check-up can determine whether they have been infected again. For screening tests, there is only a certain degree of false positives that can be allowed.


　Now that there is a cure for chronic hepatitis C, it has become a treatable disease. For those who have never taken a hepatitis test before, it is recommended to at least get tested once in a lifetime. There are many local governments that have subsidized costs for testing. However, right now, the spread of COVID-19 is still rampant, so it is advisable to get tested after the pandemic has died down.


A PCR test will be conducted first for HCV if there is a demand for higher safety precautions like the ones used in blood transfusion. However, if it is a screening test for Hepatitis B, an antigen test will be used. After considering the distinct characteristics of different diseases and tests, an appropriate test must be used that fits its specific purpose.


Source: https://www.asahi.com/articles/ASN7K42WZN7KUBQU001.html?iref=com_apitop