June 28, 2021 Serology tests detect antibodies in the patient's blood sample- antibodies being the soldiers of the immune system which help the body defeat invaders. Lianhe Zaobao SINGAPORE - People who are fully vaccinated against Covid-19 generally do not get seriously ill even if they get infected with the virus. However, they could still transmit it to others. Associate Professor Raymond Lin, director of the National Centre for Infectious Diseases (NCID) National Public Health Laboratory, told The Straits Times that this was the centre's observation from studying the serology test results of those diagnosed with Covid-19. Serology tests detect antibodies in the patient's blood sample - antibodies being the soldiers of the immune system which help the body defeat the invader.