Kyodo reported that the Health Ministry is weighing the idea of rolling out an antigen test designed to detect the presence (or absence) of an antigen, a structure within a virus that triggers the immune system’s response to fight off an infection. As antigens can be detected almost immediately after infection, the test can reportedly tell much sooner whether someone has the virus. Antigen tests are used to diagnose influenza. As a testing kit is expected to be developed soon, the Ministry is reportedly looking to approve the use of the kit in May. The article added that since the antigen test may be less accurate than the PCR diagnostic test, the ministry is likely to examine carefully to whom the antigen test will be administered.